diff --git a/src/hmr/hotModuleReplacement.js b/src/hmr/hotModuleReplacement.js
index 26075537..e94dba9d 100644
--- a/src/hmr/hotModuleReplacement.js
+++ b/src/hmr/hotModuleReplacement.js
@@ -5,9 +5,6 @@
   func-names
 */
 
-// eslint-disable-next-line jsdoc/no-restricted-syntax
-/** @typedef {any} TODO */
-
 const normalizeUrl = require("./normalize-url");
 
 const srcByModuleId = Object.create(null);
@@ -47,9 +44,11 @@ function debounce(fn, time) {
  */
 function noop() {}
 
+/** @typedef {(filename?: string) => string[]} GetScriptSrc */
+
 /**
  * @param {string | number} moduleId a module id
- * @returns {TODO} current script url
+ * @returns {GetScriptSrc} current script url
  */
 function getCurrentScriptUrl(moduleId) {
   let src = srcByModuleId[moduleId];
@@ -69,13 +68,10 @@ function getCurrentScriptUrl(moduleId) {
     srcByModuleId[moduleId] = src;
   }
 
-  /**
-   * @param {string} fileMap file map
-   * @returns {null | string[]} normalized files
-   */
+  /** @type {GetScriptSrc} */
   return function (fileMap) {
     if (!src) {
-      return null;
+      return [];
     }
 
     const splitResult = src.split(/([^\\/]+)\.js$/);
@@ -114,8 +110,10 @@ function isUrlRequest(url) {
   return true;
 }
 
+/** @typedef {HTMLLinkElement & { isLoaded: boolean, visited: boolean }} HotHTMLLinkElement */
+
 /**
- * @param {TODO} el html link element
+ * @param {HotHTMLLinkElement} el html link element
  * @param {string=} url a URL
  */
 function updateCss(el, url) {
@@ -145,7 +143,9 @@ function updateCss(el, url) {
 
   el.visited = true;
 
-  const newEl = el.cloneNode();
+  const newEl =
+    /** @type {HotHTMLLinkElement} */
+    (el.cloneNode());
 
   newEl.isLoaded = false;
 
@@ -155,7 +155,10 @@ function updateCss(el, url) {
     }
 
     newEl.isLoaded = true;
-    el.parentNode.removeChild(el);
+
+    if (el.parentNode) {
+      el.parentNode.removeChild(el);
+    }
   });
 
   newEl.addEventListener("error", () => {
@@ -164,21 +167,26 @@ function updateCss(el, url) {
     }
 
     newEl.isLoaded = true;
-    el.parentNode.removeChild(el);
+
+    if (el.parentNode) {
+      el.parentNode.removeChild(el);
+    }
   });
 
   newEl.href = `${url}?${Date.now()}`;
 
-  if (el.nextSibling) {
-    el.parentNode.insertBefore(newEl, el.nextSibling);
-  } else {
-    el.parentNode.appendChild(newEl);
+  if (el.parentNode) {
+    if (el.nextSibling) {
+      el.parentNode.insertBefore(newEl, el.nextSibling);
+    } else {
+      el.parentNode.appendChild(newEl);
+    }
   }
 }
 
 /**
  * @param {string} href href
- * @param {TODO} src src
+ * @param {string[]} src src
  * @returns {undefined | string} a reload url
  */
 function getReloadUrl(href, src) {
@@ -192,6 +200,7 @@ function getReloadUrl(href, src) {
      */
     // eslint-disable-next-line array-callback-return
     (url) => {
+      // @ts-expect-error fix me in the next major release
       // eslint-disable-next-line unicorn/prefer-includes
       if (href.indexOf(src) > -1) {
         ret = url;
@@ -203,14 +212,10 @@ function getReloadUrl(href, src) {
 }
 
 /**
- * @param {string=} src source
+ * @param {string[]} src source
  * @returns {boolean} true when loaded, otherwise false
  */
 function reloadStyle(src) {
-  if (!src) {
-    return false;
-  }
-
   const elements = document.querySelectorAll("link");
   let loaded = false;
 
@@ -256,8 +261,8 @@ function reloadAll() {
 
 /**
  * @param {number | string} moduleId a module id
- * @param {TODO} options options
- * @returns {TODO} wrapper function
+ * @param {{ filename?: string, locals?: boolean }} options options
+ * @returns {() => void} wrapper function
  */
 module.exports = function (moduleId, options) {
   if (noDocument) {
diff --git a/src/index.js b/src/index.js
index 19329234..944a33aa 100644
--- a/src/index.js
+++ b/src/index.js
@@ -21,7 +21,7 @@ const {
 /** @typedef {import("webpack").Compilation} Compilation */
 /** @typedef {import("webpack").ChunkGraph} ChunkGraph */
 /** @typedef {import("webpack").Chunk} Chunk */
-/** @typedef {Parameters<import("webpack").Chunk["isInGroup"]>[0]} ChunkGroup */
+/** @typedef {import("webpack").ChunkGroup} ChunkGroup */
 /** @typedef {import("webpack").Module} Module */
 /** @typedef {import("webpack").Dependency} Dependency */
 /** @typedef {import("webpack").sources.Source} Source */
@@ -30,6 +30,9 @@ const {
 /** @typedef {import("webpack").AssetInfo} AssetInfo */
 /** @typedef {import("./loader.js").Dependency} LoaderDependency */
 
+/** @typedef {NonNullable<Required<Configuration>['output']['filename']>} Filename */
+/** @typedef {NonNullable<Required<Configuration>['output']['chunkFilename']>} ChunkFilename */
+
 /**
  * @typedef {object} LoaderOptions
  * @property {string | ((resourcePath: string, rootContext: string) => string)=} publicPath public path
@@ -41,8 +44,8 @@ const {
 
 /**
  * @typedef {object} PluginOptions
- * @property {Required<Configuration>['output']['filename']=} filename filename
- * @property {Required<Configuration>['output']['chunkFilename']=} chunkFilename chunk filename
+ * @property {Filename=} filename filename
+ * @property {ChunkFilename=} chunkFilename chunk filename
  * @property {boolean=} ignoreOrder true when need to ignore order, otherwise false
  * @property {string | ((linkTag: HTMLLinkElement) => void)=} insert link insert place or a custom insert function
  * @property {Record<string, string>=} attributes link attributes
@@ -53,8 +56,8 @@ const {
 
 /**
  * @typedef {object} NormalizedPluginOptions
- * @property {Required<Configuration>['output']['filename']} filename filename
- * @property {Required<Configuration>['output']['chunkFilename']=} chunkFilename chunk filename
+ * @property {Filename} filename filename
+ * @property {ChunkFilename=} chunkFilename chunk filename
  * @property {boolean} ignoreOrder true when need to ignore order, otherwise false
  * @property {string | ((linkTag: HTMLLinkElement) => void)=} insert a link insert place or a custom insert function
  * @property {Record<string, string>=} attributes link attributes
@@ -70,9 +73,6 @@ const {
  * @property {Record<string, string>=} attributes link attributes
  */
 
-// eslint-disable-next-line jsdoc/no-restricted-syntax
-/** @typedef {any} TODO */
-
 const pluginName = "mini-css-extract-plugin";
 const pluginSymbol = Symbol(pluginName);
 
@@ -89,8 +89,9 @@ const CODE_GENERATION_RESULT = {
   runtimeRequirements: new Set(),
 };
 
-/** @typedef {Module & { content: Buffer, media?: string, sourceMap?: Buffer, supports?: string, layer?: string, assets?: { [key: string]: TODO }, assetsInfo?: Map<string, AssetInfo> }} CssModule */
-/** @typedef {{ context: string | null, identifier: string, identifierIndex: number, content: Buffer, sourceMap?: Buffer, media?: string, supports?: string, layer?: TODO, assetsInfo?: Map<string, AssetInfo>, assets?: { [key: string]: TODO }}} CssModuleDependency */
+// eslint-disable-next-line jsdoc/no-restricted-syntax
+/** @typedef {{ context: string | null, identifier: string, identifierIndex: number, content: Buffer, sourceMap?: Buffer, media?: string, supports?: string, layer?: any, assetsInfo?: Map<string, AssetInfo>, assets?: { [key: string]: Source }}} CssModuleDependency */
+/** @typedef {Module & { content: Buffer, media?: string, sourceMap?: Buffer, supports?: string, layer?: string, assets?: { [key: string]: Source }, assetsInfo?: Map<string, AssetInfo> }} CssModule */
 /** @typedef {{ new(dependency: CssModuleDependency): CssModule }} CssModuleConstructor */
 /** @typedef {Dependency & CssModuleDependency} CssDependency */
 /** @typedef {Omit<LoaderDependency, "context">} CssDependencyOptions */
@@ -437,10 +438,8 @@ class MiniCssExtractPlugin {
         this.sourceMap = sourceMap;
         this.context = context;
         /** @type {{ [key: string]: Source } | undefined}} */
-
         this.assets = undefined;
         /** @type {Map<string, AssetInfo> | undefined} */
-
         this.assetsInfo = undefined;
       }
 
@@ -486,7 +485,6 @@ class MiniCssExtractPlugin {
       }
     }
 
-    // @ts-expect-error
     cssDependencyCache.set(webpack, CssDependency);
 
     webpack.util.serialization.register(
@@ -525,7 +523,6 @@ class MiniCssExtractPlugin {
       },
     );
 
-    // @ts-expect-error
     return CssDependency;
   }
 
@@ -574,7 +571,6 @@ class MiniCssExtractPlugin {
       filename: DEFAULT_FILENAME,
       ignoreOrder: false,
       // TODO remove in the next major release
-
       experimentalUseImportModule: undefined,
       runtime: true,
       ...options,
@@ -639,7 +635,7 @@ class MiniCssExtractPlugin {
     ) {
       /** @type {Compiler["options"]["experiments"] & { executeModule?: boolean }} */
 
-      // @ts-expect-error
+      // @ts-expect-error TODO remove in the next major release
       compiler.options.experiments.executeModule = true;
     }
 
@@ -692,7 +688,7 @@ class MiniCssExtractPlugin {
       class CssModuleFactory {
         /**
          * @param {{ dependencies: Dependency[] }} dependencies
-         * @param {(arg0?: Error, arg1?: TODO) => void} callback
+         * @param {(err?: null | Error, result?: CssModule) => void} callback
          */
 
         create({ dependencies: [dependency] }, callback) {
@@ -705,6 +701,7 @@ class MiniCssExtractPlugin {
 
       compilation.dependencyFactories.set(
         CssDependency,
+        // @ts-expect-error TODO fix in the next major release and fix using `CssModuleFactory extends webpack.ModuleFactory`
         new CssModuleFactory(),
       );
 
@@ -722,7 +719,7 @@ class MiniCssExtractPlugin {
         /**
          * @param {ReturnType<Compilation["getRenderManifest"]>} result result
          * @param {Parameters<Compilation["getRenderManifest"]>[0]} chunk chunk
-         * @returns {TODO} a rendered manifest
+         * @returns {ReturnType<Compilation["getRenderManifest"]>} a rendered manifest
          */
         (result, { chunk }) => {
           const { chunkGraph } = compilation;
@@ -731,7 +728,7 @@ class MiniCssExtractPlugin {
           // We don't need hot update chunks for css
           // We will use the real asset instead to update
           if (chunk instanceof HotUpdateChunk) {
-            return;
+            return result;
           }
 
           const renderedModules =
@@ -774,6 +771,8 @@ class MiniCssExtractPlugin {
               hash: chunk.contentHash[MODULE_TYPE],
             });
           }
+
+          return result;
         },
       );
 
@@ -1232,7 +1231,7 @@ class MiniCssExtractPlugin {
             `${RuntimeGlobals.require}.miniCssF`,
             /**
              * @param {Chunk} referencedChunk a referenced chunk
-             * @returns {TODO} a template value
+             * @returns {ReturnType<import("webpack").runtime.GetChunkFilenameRuntimeModule["getFilenameForChunk"]>} a template value
              */
             (referencedChunk) => {
               if (!referencedChunk.contentHash[MODULE_TYPE]) {
@@ -1240,8 +1239,8 @@ class MiniCssExtractPlugin {
               }
 
               return referencedChunk.canBeInitial()
-                ? this.options.filename
-                : this.options.chunkFilename;
+                ? /** @type {Filename} */ (this.options.filename)
+                : /** @type {ChunkFilename} */ (this.options.chunkFilename);
             },
             set.has(RuntimeGlobals.hmrDownloadUpdateHandlers),
           ),
diff --git a/src/loader.js b/src/loader.js
index 579f0062..4c69bbef 100644
--- a/src/loader.js
+++ b/src/loader.js
@@ -28,13 +28,13 @@ const MiniCssExtractPlugin = require("./index");
 /** @typedef {{[key: string]: string | Function }} Locals */
 
 // eslint-disable-next-line jsdoc/no-restricted-syntax
-/** @typedef {any} TODO */
+/** @typedef {any} EXPECTED_ANY */
 
 /**
  * @typedef {object} Dependency
  * @property {string} identifier identifier
  * @property {string | null} context context
- * @property {Buffer=} content content
+ * @property {Buffer} content content
  * @property {string=} media media
  * @property {string=} supports supports
  * @property {string=} layer layer
@@ -104,9 +104,9 @@ function pitch(request) {
   const options = this.getOptions(/** @type {Schema} */ (schema));
   const emit = typeof options.emit !== "undefined" ? options.emit : true;
   const callback = this.async();
-  const optionsFromPlugin = /** @type {TODO} */ (this)[
-    MiniCssExtractPlugin.pluginSymbol
-  ];
+  const optionsFromPlugin =
+    // @ts-expect-error
+    this[MiniCssExtractPlugin.pluginSymbol];
 
   if (!optionsFromPlugin) {
     callback(
@@ -121,7 +121,7 @@ function pitch(request) {
   const { webpack } = /** @type {Compiler} */ (this._compiler);
 
   /**
-   * @param {TODO} originalExports original exports
+   * @param {EXPECTED_ANY} originalExports original exports
    * @param {Compilation=} compilation compilation
    * @param {{ [name: string]: Source }=} assets assets
    * @param {Map<string, AssetInfo>=} assetsInfo assets info
@@ -201,14 +201,15 @@ function pitch(request) {
               locals = {};
             }
 
-            /** @type {Locals} */ (locals)[key] = originalExports[key];
+            /** @type {Locals} */
+            (locals)[key] = originalExports[key];
           }
         }
       } else {
         locals = exports && exports.locals;
       }
 
-      /** @type {Dependency[] | [null, TODO][]} */
+      /** @type {Dependency[] | [null, Record<string, string>][]} */
       let dependencies;
 
       if (!Array.isArray(exports)) {
diff --git a/test/cases/hmr-locals/expected/main.js b/test/cases/hmr-locals/expected/main.js
index 380fd841..508bacdd 100644
--- a/test/cases/hmr-locals/expected/main.js
+++ b/test/cases/hmr-locals/expected/main.js
@@ -14,9 +14,6 @@
   func-names
 */
 
-// eslint-disable-next-line jsdoc/no-restricted-syntax
-/** @typedef {any} TODO */
-
 const normalizeUrl = __webpack_require__(/*! ./normalize-url */ "../../../src/hmr/normalize-url.js");
 
 const srcByModuleId = Object.create(null);
@@ -56,9 +53,11 @@ function debounce(fn, time) {
  */
 function noop() {}
 
+/** @typedef {(filename?: string) => string[]} GetScriptSrc */
+
 /**
  * @param {string | number} moduleId a module id
- * @returns {TODO} current script url
+ * @returns {GetScriptSrc} current script url
  */
 function getCurrentScriptUrl(moduleId) {
   let src = srcByModuleId[moduleId];
@@ -78,13 +77,10 @@ function getCurrentScriptUrl(moduleId) {
     srcByModuleId[moduleId] = src;
   }
 
-  /**
-   * @param {string} fileMap file map
-   * @returns {null | string[]} normalized files
-   */
+  /** @type {GetScriptSrc} */
   return function (fileMap) {
     if (!src) {
-      return null;
+      return [];
     }
 
     const splitResult = src.split(/([^\\/]+)\.js$/);
@@ -123,8 +119,10 @@ function isUrlRequest(url) {
   return true;
 }
 
+/** @typedef {HTMLLinkElement & { isLoaded: boolean, visited: boolean }} HotHTMLLinkElement */
+
 /**
- * @param {TODO} el html link element
+ * @param {HotHTMLLinkElement} el html link element
  * @param {string=} url a URL
  */
 function updateCss(el, url) {
@@ -154,7 +152,9 @@ function updateCss(el, url) {
 
   el.visited = true;
 
-  const newEl = el.cloneNode();
+  const newEl =
+    /** @type {HotHTMLLinkElement} */
+    (el.cloneNode());
 
   newEl.isLoaded = false;
 
@@ -164,7 +164,10 @@ function updateCss(el, url) {
     }
 
     newEl.isLoaded = true;
-    el.parentNode.removeChild(el);
+
+    if (el.parentNode) {
+      el.parentNode.removeChild(el);
+    }
   });
 
   newEl.addEventListener("error", () => {
@@ -173,21 +176,26 @@ function updateCss(el, url) {
     }
 
     newEl.isLoaded = true;
-    el.parentNode.removeChild(el);
+
+    if (el.parentNode) {
+      el.parentNode.removeChild(el);
+    }
   });
 
   newEl.href = `${url}?${Date.now()}`;
 
-  if (el.nextSibling) {
-    el.parentNode.insertBefore(newEl, el.nextSibling);
-  } else {
-    el.parentNode.appendChild(newEl);
+  if (el.parentNode) {
+    if (el.nextSibling) {
+      el.parentNode.insertBefore(newEl, el.nextSibling);
+    } else {
+      el.parentNode.appendChild(newEl);
+    }
   }
 }
 
 /**
  * @param {string} href href
- * @param {TODO} src src
+ * @param {string[]} src src
  * @returns {undefined | string} a reload url
  */
 function getReloadUrl(href, src) {
@@ -201,6 +209,7 @@ function getReloadUrl(href, src) {
      */
     // eslint-disable-next-line array-callback-return
     (url) => {
+      // @ts-expect-error fix me in the next major release
       // eslint-disable-next-line unicorn/prefer-includes
       if (href.indexOf(src) > -1) {
         ret = url;
@@ -212,14 +221,10 @@ function getReloadUrl(href, src) {
 }
 
 /**
- * @param {string=} src source
+ * @param {string[]} src source
  * @returns {boolean} true when loaded, otherwise false
  */
 function reloadStyle(src) {
-  if (!src) {
-    return false;
-  }
-
   const elements = document.querySelectorAll("link");
   let loaded = false;
 
@@ -265,8 +270,8 @@ function reloadAll() {
 
 /**
  * @param {number | string} moduleId a module id
- * @param {TODO} options options
- * @returns {TODO} wrapper function
+ * @param {{ filename?: string, locals?: boolean }} options options
+ * @returns {() => void} wrapper function
  */
 module.exports = function (moduleId, options) {
   if (noDocument) {
diff --git a/test/cases/hmr/expected/main.js b/test/cases/hmr/expected/main.js
index d44d58dc..3e706ffb 100644
--- a/test/cases/hmr/expected/main.js
+++ b/test/cases/hmr/expected/main.js
@@ -14,9 +14,6 @@
   func-names
 */
 
-// eslint-disable-next-line jsdoc/no-restricted-syntax
-/** @typedef {any} TODO */
-
 const normalizeUrl = __webpack_require__(/*! ./normalize-url */ "../../../src/hmr/normalize-url.js");
 
 const srcByModuleId = Object.create(null);
@@ -56,9 +53,11 @@ function debounce(fn, time) {
  */
 function noop() {}
 
+/** @typedef {(filename?: string) => string[]} GetScriptSrc */
+
 /**
  * @param {string | number} moduleId a module id
- * @returns {TODO} current script url
+ * @returns {GetScriptSrc} current script url
  */
 function getCurrentScriptUrl(moduleId) {
   let src = srcByModuleId[moduleId];
@@ -78,13 +77,10 @@ function getCurrentScriptUrl(moduleId) {
     srcByModuleId[moduleId] = src;
   }
 
-  /**
-   * @param {string} fileMap file map
-   * @returns {null | string[]} normalized files
-   */
+  /** @type {GetScriptSrc} */
   return function (fileMap) {
     if (!src) {
-      return null;
+      return [];
     }
 
     const splitResult = src.split(/([^\\/]+)\.js$/);
@@ -123,8 +119,10 @@ function isUrlRequest(url) {
   return true;
 }
 
+/** @typedef {HTMLLinkElement & { isLoaded: boolean, visited: boolean }} HotHTMLLinkElement */
+
 /**
- * @param {TODO} el html link element
+ * @param {HotHTMLLinkElement} el html link element
  * @param {string=} url a URL
  */
 function updateCss(el, url) {
@@ -154,7 +152,9 @@ function updateCss(el, url) {
 
   el.visited = true;
 
-  const newEl = el.cloneNode();
+  const newEl =
+    /** @type {HotHTMLLinkElement} */
+    (el.cloneNode());
 
   newEl.isLoaded = false;
 
@@ -164,7 +164,10 @@ function updateCss(el, url) {
     }
 
     newEl.isLoaded = true;
-    el.parentNode.removeChild(el);
+
+    if (el.parentNode) {
+      el.parentNode.removeChild(el);
+    }
   });
 
   newEl.addEventListener("error", () => {
@@ -173,21 +176,26 @@ function updateCss(el, url) {
     }
 
     newEl.isLoaded = true;
-    el.parentNode.removeChild(el);
+
+    if (el.parentNode) {
+      el.parentNode.removeChild(el);
+    }
   });
 
   newEl.href = `${url}?${Date.now()}`;
 
-  if (el.nextSibling) {
-    el.parentNode.insertBefore(newEl, el.nextSibling);
-  } else {
-    el.parentNode.appendChild(newEl);
+  if (el.parentNode) {
+    if (el.nextSibling) {
+      el.parentNode.insertBefore(newEl, el.nextSibling);
+    } else {
+      el.parentNode.appendChild(newEl);
+    }
   }
 }
 
 /**
  * @param {string} href href
- * @param {TODO} src src
+ * @param {string[]} src src
  * @returns {undefined | string} a reload url
  */
 function getReloadUrl(href, src) {
@@ -201,6 +209,7 @@ function getReloadUrl(href, src) {
      */
     // eslint-disable-next-line array-callback-return
     (url) => {
+      // @ts-expect-error fix me in the next major release
       // eslint-disable-next-line unicorn/prefer-includes
       if (href.indexOf(src) > -1) {
         ret = url;
@@ -212,14 +221,10 @@ function getReloadUrl(href, src) {
 }
 
 /**
- * @param {string=} src source
+ * @param {string[]} src source
  * @returns {boolean} true when loaded, otherwise false
  */
 function reloadStyle(src) {
-  if (!src) {
-    return false;
-  }
-
   const elements = document.querySelectorAll("link");
   let loaded = false;
 
@@ -265,8 +270,8 @@ function reloadAll() {
 
 /**
  * @param {number | string} moduleId a module id
- * @param {TODO} options options
- * @returns {TODO} wrapper function
+ * @param {{ filename?: string, locals?: boolean }} options options
+ * @returns {() => void} wrapper function
  */
 module.exports = function (moduleId, options) {
   if (noDocument) {
diff --git a/types/hmr/hotModuleReplacement.d.ts b/types/hmr/hotModuleReplacement.d.ts
index 8f72d9f8..b8238313 100644
--- a/types/hmr/hotModuleReplacement.d.ts
+++ b/types/hmr/hotModuleReplacement.d.ts
@@ -1,6 +1,16 @@
 declare namespace _exports {
-  export { TODO };
+  export { GetScriptSrc, HotHTMLLinkElement };
 }
-declare function _exports(moduleId: number | string, options: TODO): TODO;
+declare function _exports(
+  moduleId: number | string,
+  options: {
+    filename?: string;
+    locals?: boolean;
+  },
+): () => void;
 export = _exports;
-type TODO = any;
+type GetScriptSrc = (filename?: string) => string[];
+type HotHTMLLinkElement = HTMLLinkElement & {
+  isLoaded: boolean;
+  visited: boolean;
+};
diff --git a/types/index.d.ts b/types/index.d.ts
index bf2a3d83..ad31d5ee 100644
--- a/types/index.d.ts
+++ b/types/index.d.ts
@@ -90,13 +90,14 @@ declare namespace MiniCssExtractPlugin {
     WebpackError,
     AssetInfo,
     LoaderDependency,
+    Filename,
+    ChunkFilename,
     LoaderOptions,
     PluginOptions,
     NormalizedPluginOptions,
     RuntimeOptions,
-    TODO,
-    CssModule,
     CssModuleDependency,
+    CssModule,
     CssModuleConstructor,
     CssDependency,
     CssDependencyOptions,
@@ -110,7 +111,7 @@ declare namespace MiniCssExtractPlugin {
 /** @typedef {import("webpack").Compilation} Compilation */
 /** @typedef {import("webpack").ChunkGraph} ChunkGraph */
 /** @typedef {import("webpack").Chunk} Chunk */
-/** @typedef {Parameters<import("webpack").Chunk["isInGroup"]>[0]} ChunkGroup */
+/** @typedef {import("webpack").ChunkGroup} ChunkGroup */
 /** @typedef {import("webpack").Module} Module */
 /** @typedef {import("webpack").Dependency} Dependency */
 /** @typedef {import("webpack").sources.Source} Source */
@@ -118,6 +119,8 @@ declare namespace MiniCssExtractPlugin {
 /** @typedef {import("webpack").WebpackError} WebpackError */
 /** @typedef {import("webpack").AssetInfo} AssetInfo */
 /** @typedef {import("./loader.js").Dependency} LoaderDependency */
+/** @typedef {NonNullable<Required<Configuration>['output']['filename']>} Filename */
+/** @typedef {NonNullable<Required<Configuration>['output']['chunkFilename']>} ChunkFilename */
 /**
  * @typedef {object} LoaderOptions
  * @property {string | ((resourcePath: string, rootContext: string) => string)=} publicPath public path
@@ -128,8 +131,8 @@ declare namespace MiniCssExtractPlugin {
  */
 /**
  * @typedef {object} PluginOptions
- * @property {Required<Configuration>['output']['filename']=} filename filename
- * @property {Required<Configuration>['output']['chunkFilename']=} chunkFilename chunk filename
+ * @property {Filename=} filename filename
+ * @property {ChunkFilename=} chunkFilename chunk filename
  * @property {boolean=} ignoreOrder true when need to ignore order, otherwise false
  * @property {string | ((linkTag: HTMLLinkElement) => void)=} insert link insert place or a custom insert function
  * @property {Record<string, string>=} attributes link attributes
@@ -139,8 +142,8 @@ declare namespace MiniCssExtractPlugin {
  */
 /**
  * @typedef {object} NormalizedPluginOptions
- * @property {Required<Configuration>['output']['filename']} filename filename
- * @property {Required<Configuration>['output']['chunkFilename']=} chunkFilename chunk filename
+ * @property {Filename} filename filename
+ * @property {ChunkFilename=} chunkFilename chunk filename
  * @property {boolean} ignoreOrder true when need to ignore order, otherwise false
  * @property {string | ((linkTag: HTMLLinkElement) => void)=} insert a link insert place or a custom insert function
  * @property {Record<string, string>=} attributes link attributes
@@ -154,7 +157,6 @@ declare namespace MiniCssExtractPlugin {
  * @property {string | false | 'text/css'} linkType value of a link type attribute
  * @property {Record<string, string>=} attributes link attributes
  */
-/** @typedef {any} TODO */
 declare const pluginName: "mini-css-extract-plugin";
 declare const pluginSymbol: unique symbol;
 declare var loader: string;
@@ -163,7 +165,7 @@ type Compiler = import("webpack").Compiler;
 type Compilation = import("webpack").Compilation;
 type ChunkGraph = import("webpack").ChunkGraph;
 type Chunk = import("webpack").Chunk;
-type ChunkGroup = Parameters<import("webpack").Chunk["isInGroup"]>[0];
+type ChunkGroup = import("webpack").ChunkGroup;
 type Module = import("webpack").Module;
 type Dependency = import("webpack").Dependency;
 type Source = import("webpack").sources.Source;
@@ -171,6 +173,10 @@ type Configuration = import("webpack").Configuration;
 type WebpackError = import("webpack").WebpackError;
 type AssetInfo = import("webpack").AssetInfo;
 type LoaderDependency = import("./loader.js").Dependency;
+type Filename = NonNullable<Required<Configuration>["output"]["filename"]>;
+type ChunkFilename = NonNullable<
+  Required<Configuration>["output"]["chunkFilename"]
+>;
 type LoaderOptions = {
   /**
    * public path
@@ -199,13 +205,11 @@ type PluginOptions = {
   /**
    * filename
    */
-  filename?: Required<Configuration>["output"]["filename"] | undefined;
+  filename?: Filename | undefined;
   /**
    * chunk filename
    */
-  chunkFilename?:
-    | Required<Configuration>["output"]["chunkFilename"]
-    | undefined;
+  chunkFilename?: ChunkFilename | undefined;
   /**
    * true when need to ignore order, otherwise false
    */
@@ -235,13 +239,11 @@ type NormalizedPluginOptions = {
   /**
    * filename
    */
-  filename: Required<Configuration>["output"]["filename"];
+  filename: Filename;
   /**
    * chunk filename
    */
-  chunkFilename?:
-    | Required<Configuration>["output"]["chunkFilename"]
-    | undefined;
+  chunkFilename?: ChunkFilename | undefined;
   /**
    * true when need to ignore order, otherwise false
    */
@@ -281,18 +283,6 @@ type RuntimeOptions = {
    */
   attributes?: Record<string, string> | undefined;
 };
-type TODO = any;
-type CssModule = Module & {
-  content: Buffer;
-  media?: string;
-  sourceMap?: Buffer;
-  supports?: string;
-  layer?: string;
-  assets?: {
-    [key: string]: TODO;
-  };
-  assetsInfo?: Map<string, AssetInfo>;
-};
 type CssModuleDependency = {
   context: string | null;
   identifier: string;
@@ -301,11 +291,22 @@ type CssModuleDependency = {
   sourceMap?: Buffer;
   media?: string;
   supports?: string;
-  layer?: TODO;
+  layer?: any;
   assetsInfo?: Map<string, AssetInfo>;
   assets?: {
-    [key: string]: TODO;
+    [key: string]: Source;
+  };
+};
+type CssModule = Module & {
+  content: Buffer;
+  media?: string;
+  sourceMap?: Buffer;
+  supports?: string;
+  layer?: string;
+  assets?: {
+    [key: string]: Source;
   };
+  assetsInfo?: Map<string, AssetInfo>;
 };
 type CssModuleConstructor = {
   new (dependency: CssModuleDependency): CssModule;
diff --git a/types/loader.d.ts b/types/loader.d.ts
index f111cbfc..11c90aa6 100644
--- a/types/loader.d.ts
+++ b/types/loader.d.ts
@@ -22,7 +22,7 @@ declare namespace loader {
     NormalModule,
     LoaderOptions,
     Locals,
-    TODO,
+    EXPECTED_ANY,
     Dependency,
   };
 }
@@ -37,12 +37,12 @@ import MiniCssExtractPlugin = require("./index");
 /** @typedef {import("webpack").NormalModule} NormalModule */
 /** @typedef {import("./index.js").LoaderOptions} LoaderOptions */
 /** @typedef {{[key: string]: string | Function }} Locals */
-/** @typedef {any} TODO */
+/** @typedef {any} EXPECTED_ANY */
 /**
  * @typedef {object} Dependency
  * @property {string} identifier identifier
  * @property {string | null} context context
- * @property {Buffer=} content content
+ * @property {Buffer} content content
  * @property {string=} media media
  * @property {string=} supports supports
  * @property {string=} layer layer
@@ -81,7 +81,7 @@ type LoaderOptions = import("./index.js").LoaderOptions;
 type Locals = {
   [key: string]: string | Function;
 };
-type TODO = any;
+type EXPECTED_ANY = any;
 type Dependency = {
   /**
    * identifier
@@ -94,7 +94,7 @@ type Dependency = {
   /**
    * content
    */
-  content?: Buffer | undefined;
+  content: Buffer;
   /**
    * media
    */