Fix TS error in core

Author: hasparus

packages/core/package.json

@@ -25,6 +25,7 @@
     "react": "^16.11.0"
   },
   "devDependencies": {
+    "@types/react": "^16.9.19",
     "react": "^16.11.0"
   }
 }

packages/core/src/index.ts

@@ -60,10 +60,11 @@ const isMergeableObject = n => {
 
 const arrayMerge = (destinationArray, sourceArray, options) => sourceArray
 
-export const merge = (a, b) =>
+export const merge = <T>(a: Partial<T>, b: Partial<T>): T =>
   deepmerge(a, b, { isMergeableObject, arrayMerge })
 
-merge.all = (...args) => deepmerge.all(args, { isMergeableObject, arrayMerge })
+merge.all = <T>(...args: Partial<T>[]) =>
+  deepmerge.all<T>(args, { isMergeableObject, arrayMerge })
 
 interface BaseProviderProps {
   context: ContextValue
@@ -99,7 +100,7 @@ export function ThemeProvider({ theme, children }: ThemeProviderProps) {
   const context =
     typeof theme === 'function'
       ? { ...outer, theme: theme(outer.theme) }
-      : merge.all({}, outer, { theme })
+      : merge.all<ContextValue>({}, outer, { theme })
 
   return jsx(BaseProvider, { context }, children)
 }

packages/core/src/theme.d.ts renamed to packages/core/src/theme.ts

@@ -1,6 +1,7 @@
 {
   "compilerOptions": {
     "resolveJsonModule": true,
-    "esModuleInterop": true
+    "esModuleInterop": true,
+    "moduleResolution": "node"
   }
 }

packages/core/tsconfig.json

@@ -3549,6 +3549,14 @@
     "@types/prop-types" "*"
     csstype "^2.2.0"
 
+"@types/react@^16.9.19":
+  version "16.9.19"
+  resolved "https://registry.yarnpkg.com/@types/react/-/react-16.9.19.tgz#c842aa83ea490007d29938146ff2e4d9e4360c40"
+  integrity sha512-LJV97//H+zqKWMms0kvxaKYJDG05U2TtQB3chRLF8MPNs+MQh/H1aGlyDUxjaHvu08EAGerdX2z4LTBc7ns77A==
+  dependencies:
+    "@types/prop-types" "*"
+    csstype "^2.2.0"
+
 "@types/[email protected]":
   version "0.0.8"
   resolved "https://registry.yarnpkg.com/@types/resolve/-/resolve-0.0.8.tgz#f26074d238e02659e323ce1a13d041eee280e194"