Language server raises exception when client does not have any configuration settings to provide it.

[cowboyd]

Error: Request textDocument/codeAction failed with message: Cannot read properties of null (reading 'workingDirectory')

I'm trying to get the vscode-eslint server working with the Emacs eglot client. However, it is raising an exception because of what is apparently a null settings for the requested file. If I understand the spec correctly however, Eglot's behavior is ok.

If the client can’t provide a configuration setting for a given scope then null needs to be present in the returned array.

Here is the full transcript of the conversation between Eglot and vscode-eslint. As you can see at the end, it apparently requests the configuration as part of responding to the textDocument/codeAction request. When Eglot responds that is has no further configuration available by returning null, the textDocument/codeAction request fails with the above exception.

One further note: Eglot does issue this warning as part of the transcript: [eglot] (warning) Server tried to register unsupported capability ‘workspace/didChangeWorkspaceFolders’.

In the transcript --> represents an outgoing request, and <-- represents a response to a previous request. Notifications are always ongoing -->

 --> [client2server.request] [ "vscode-eslint-language-server" ] initialize [
   {
     processId: 34058,
     clientInfo: { name: "Eglot", version: "1.18.0.20250408.74617" },
     rootPath: "/Users/cowboyd/Code/@cowboyd/react-ts-eslint-prettier-sample/",
     rootUri: "file:///Users/cowboyd/Code/@cowboyd/react-ts-eslint-prettier-sample",
     initializationOptions: {},
     capabilities: {
       workspace: {
         applyEdit: true,
         executeCommand: { dynamicRegistration: false },
         workspaceEdit: { documentChanges: true },
         didChangeWatchedFiles: { dynamicRegistration: true },
         symbol: { dynamicRegistration: false },
         configuration: true,
         workspaceFolders: true
       },
       textDocument: {
         synchronization: {
           dynamicRegistration: false,
           willSave: true,
           willSaveWaitUntil: true,
           didSave: true
         },
         completion: {
           dynamicRegistration: false,
           completionItem: [Object],
           contextSupport: true
         },
         hover: { dynamicRegistration: false, contentFormat: [Array] },
         signatureHelp: { dynamicRegistration: false, signatureInformation: [Object] },
         references: { dynamicRegistration: false },
         definition: { dynamicRegistration: false, linkSupport: true },
         declaration: { dynamicRegistration: false, linkSupport: true },
         implementation: { dynamicRegistration: false, linkSupport: true },
         typeDefinition: { dynamicRegistration: false, linkSupport: true },
         documentSymbol: {
           dynamicRegistration: false,
           hierarchicalDocumentSymbolSupport: true,
           symbolKind: [Object]
         },
         documentHighlight: { dynamicRegistration: false },
         codeAction: {
           dynamicRegistration: false,
           resolveSupport: [Object],
           dataSupport: true,
           codeActionLiteralSupport: [Object],
           isPreferredSupport: true
         },
         formatting: { dynamicRegistration: false },
         rangeFormatting: { dynamicRegistration: false },
         rename: { dynamicRegistration: false },
         inlayHint: { dynamicRegistration: false },
         callHierarchy: { dynamicRegistration: false },
         typeHierarchy: { dynamicRegistration: false },
         publishDiagnostics: {
           relatedInformation: false,
           codeDescriptionSupport: false,
           tagSupport: [Object]
         }
       },
       window: {
         showDocument: { support: true },
         showMessage: { messageActionItem: [Object] },
         workDoneProgress: true
       },
       general: { positionEncodings: [ "utf-32", "utf-8", "utf-16" ] },
       experimental: {}
     },
     workspaceFolders: [
       {
         uri: "file:///Users/cowboyd/Code/@cowboyd/react-ts-eslint-prettier-sample",
         name: "~/Code/@cowboyd/react-ts-eslint-prettier-sample/"
       }
     ]
   },
   MutableToken { _isCancelled: false }
 ]
 --> [server2client.notify] vscode-eslint-language-server window/logMessage [ { type: 3, message: "ESLint server running in node v22.9.0" } ]
 <-- [client2server.request] [ "vscode-eslint-language-server" ] initialize {
   serverInfo: { name: "lspx", version: "0.1.0" },
   capabilities: {
     textDocumentSync: {
       openClose: true,
       change: 2,
       willSaveWaitUntil: false,
       save: { includeText: false }
     },
     workspace: { workspaceFolders: { supported: true } },
     executeCommandProvider: {
       commands: [
         "eslint.applySingleFix",
         "eslint.applySuggestion",
         "eslint.applySameFixes",
         "eslint.applyAllFixes",
         "eslint.applyDisableLine",
         "eslint.applyDisableFile",
         "eslint.openRuleDoc"
       ]
     },
     diagnosticProvider: {
       identifier: "eslint",
       interFileDependencies: false,
       workspaceDiagnostics: false
     },
     codeActionProvider: { codeActionKinds: [ "quickfix", "source.fixAll.eslint" ] }
   }
 }
 --> [client2server.notify] [ "vscode-eslint-language-server" ] initialized [ {} ]
 --> [client2server.notify] [ "vscode-eslint-language-server" ] textDocument/didOpen [
   {
     textDocument: {
       uri: "file:///Users/cowboyd/Code/@cowboyd/react-ts-eslint-prettier-sample/src/App.tsx",
       version: 0,
       languageId: "typescript",
       text: 'import { useState } from "react";\n' +
         'import reactLogo from "./assets/react.svg";\n' +
         'import viteLogo from "/vite.svg";\n' +
         'import "./App.css";\n' +
         "\n" +
         "const emptyFunc = (_, a) => {\n" +
         "  return a;\n" +
         "};\n" +
         "\n" +
         "function App() {\n" +
         "           const [count, setCount] = useState(0);\n" +
         "\n" +
         "       const x: number = '1234';\n" +
         "\n" +
         "  return (\n" +
         "          <>\n" +
         "      <div>\n" +
         '        <a href="https://vite.dev" target="_blank">\n' +
         '          <img src={viteLogo} className="logo" alt="" />\n' +
         "        </a>\n" +
         '        <a href="https://react.dev" target="_blank">\n' +
         '          <img src={reactLogo} className="logo react" alt="React logo" />\n' +
         "        </a>\n" +
         "      </div>\n" +
         "      <h1>Vite + React</h1>\n" +
         '      <div className="card">\n' +
         "        <button onClick={() => setCount((count) => count + 1)}>\n" +
         "          count is {count}\n" +
         "        </button>\n" +
         "        <p>\n" +
         "          Edit <code>src/App.tsx</code> and save to test HMR\n" +
         "        </p>\n" +
         "      </div>\n" +
         '      <p className="read-the-docs">\n' +
         "        Click on the Vite and React logos to learn more\n" +
         "      </p>\n" +
         "    </>\n" +
         "  );\n" +
         "}\n" +
         "\n" +
         "export default App;\n"
     }
   }
 ]
 --> [client2server.notify] [ "vscode-eslint-language-server" ] workspace/didChangeConfiguration [ { settings: {} } ]
 --> [server2client.request] vscode-eslint-language-server client/registerCapability [
   {
     registrations: [
       {
         id: "a9cd965b-6aff-4307-930d-ba22fb57dde0",
         method: "workspace/didChangeWorkspaceFolders",
         registerOptions: {}
       }
     ]
   },
   MutableToken { _isCancelled: false }
 ]
 <-- [server2client.request] vscode-eslint-language-server client/registerCapability null
 --> [client2server.request] [ "vscode-eslint-language-server" ] textDocument/codeAction [
   {
     textDocument: {
       uri: "file:///Users/cowboyd/Code/@cowboyd/react-ts-eslint-prettier-sample/src/App.tsx"
     },
     range: {
       start: { line: 34, character: 51 },
       end: { line: 34, character: 55 }
     },
     context: { diagnostics: [], triggerKind: 2 }
   },
   MutableToken { _isCancelled: false }
 ]
 --> [server2client.request] vscode-eslint-language-server workspace/configuration [
   {
     items: [
       {
         scopeUri: "file:///Users/cowboyd/Code/@cowboyd/react-ts-eslint-prettier-sample/src/App.tsx",
         section: ""
       }
     ]
   },
   MutableToken { _isCancelled: false }
 ]
 <-- [server2client.request] vscode-eslint-language-server workspace/configuration [ null ]
 Error: Request textDocument/codeAction failed with message: Cannot read properties of null (reading 'workingDirectory')
     at handleResponse (file:///var/folders/zs/m38wmycs4pj6ymtkk3cjrp0w0000gn/T/deno-compile-lspx/.deno_compile_node_modules/localhost/vscode-jsonrpc/8.2.1/lib/common/connection.js:565:48)
     at handleMessage (file:///var/folders/zs/m38wmycs4pj6ymtkk3cjrp0w0000gn/T/deno-compile-lspx/.deno_compile_node_modules/localhost/vscode-jsonrpc/8.2.1/lib/common/connection.js:345:13)
     at processMessageQueue (file:///var/folders/zs/m38wmycs4pj6ymtkk3cjrp0w0000gn/T/deno-compile-lspx/.deno_compile_node_modules/localhost/vscode-jsonrpc/8.2.1/lib/common/connection.js:362:17)
     at file:///var/folders/zs/m38wmycs4pj6ymtkk3cjrp0w0000gn/T/deno-compile-lspx/.deno_compile_node_modules/localhost/vscode-jsonrpc/8.2.1/lib/common/connection.js:334:13
     at ext:deno_web/02_timers.js:35:14
     at eventLoopTick (ext:core/01_core.js:213:13) {
   code: -32603,
   data: undefined
 }

[dbaeumer]

The server is currently written for VS Code and no special effort has been made to make it work in other clients. I am open for PRs to make it more usable in other clients.

[cowboyd]

@dbaeumer I'd be happy to make a PR if you can point me to where the problem is happening (I assume that it's some missing configuration), and what you think the defaults I need to provide are.

[dbaeumer]

The problem is that the server expects a working directory setting when receiving the settings from the client. So the server needs to be changed to handle the case that it is null or not present. The general code with dealing with setting is here:

vscode-eslint/server/src/eslint.ts

Line 851 in c0e7537

const uri = document.uri;

[cowboyd]

@dbaeumer Thanks! I'm trying to get a checkout of the server so that I can run it and debug it locally, however, I'm not able to get the TypeScript to compile. There seems to be a clash in the global types? I've tried on node 18, 20, and 22, all with the same result:

$ node --version
v20.19.0

$ npm --version
10.8.2

$ npm ls -g
/Users/cowboyd/.volta/tools/image/node/20.19.0/lib
├── corepack@0.31.0
└── npm@10.8.2

$ npm install

[....]

$ npm run compile

npm run compile

> vscode-eslint@3.0.13 compile
> tsc -b

node_modules/@types/node/globals.d.ts:348:11 - error TS2320: Interface 'RequestInit' cannot simultaneously extend types 'RequestInit' and 'RequestInit'.
  Named property 'dispatcher' of types 'RequestInit' and 'RequestInit' are not identical.

348 interface RequestInit extends NodeJS.fetch._RequestInit {}
              ~~~~~~~~~~~

node_modules/@types/node/globals.d.ts:348:11 - error TS2320: Interface 'RequestInit' cannot simultaneously extend types 'RequestInit' and 'RequestInit'.
  Named property 'headers' of types 'RequestInit' and 'RequestInit' are not identical.

348 interface RequestInit extends NodeJS.fetch._RequestInit {}
              ~~~~~~~~~~~

node_modules/@types/node/globals.d.ts:348:11 - error TS2320: Interface 'RequestInit' cannot simultaneously extend types 'RequestInit' and 'RequestInit'.
  Named property 'signal' of types 'RequestInit' and 'RequestInit' are not identical.

348 interface RequestInit extends NodeJS.fetch._RequestInit {}
              ~~~~~~~~~~~

node_modules/@types/node/globals.d.ts:350:18 - error TS2300: Duplicate identifier 'fetch'.

350 declare function fetch(
                     ~~~~~

  ../node_modules/bun-types/fetch.d.ts:133:5
    133 var fetch: {
            ~~~~~
    'fetch' was also declared here.

node_modules/@types/node/dom-events.d.ts:116:15 - error TS2320: Interface 'EventTarget' cannot simultaneously extend types '{ addEventListener(type: string, listener: EventListener | EventListenerObject, options?: boolean | AddEventListenerOptions | undefined): void; dispatchEvent(event: Event): boolean; removeEventListener(type: string, listener: EventListener | EventListenerObject, options?: boolean | ... 1 more ... | undefined): void; }' and '_EventTarget'.
  Named property 'addEventListener' of types '{ addEventListener(type: string, listener: EventListener | EventListenerObject, options?: boolean | AddEventListenerOptions | undefined): void; dispatchEvent(event: Event): boolean; removeEventListener(type: string, listener: EventListener | EventListenerObject, options?: boolean | ... 1 more ... | undefined): void; }' and '_EventTarget' are not identical.

116     interface EventTarget extends __EventTarget {}
                  ~~~~~~~~~~~

../node_modules/bun-types/bun.d.ts:1:52 - error TS2304: Cannot find name 'ShellOutput'.

1 declare class _ShellError extends Error implements ShellOutput {
                                                     ~~~~~~~~~~~

../node_modules/bun-types/bun.d.ts:4924:30 - error TS2344: Type '"routes"' does not satisfy the constraint '"error" | "id" | "fetch" | "maxRequestBodySize" | "development"'.

4924    | (DistributedOmit<Serve, "routes"> & {
                                  ~~~~~~~~

../node_modules/bun-types/globals.d.ts:746:6 - error TS2502: 'File' is referenced directly or indirectly in its own type annotation.

746  var File: typeof File;
         ~~~~

../node_modules/bun-types/fetch.d.ts:36:1 - error TS1046: Top-level declarations in .d.ts files must start with either a 'declare' or 'export' modifier.

36 var Headers: {
   ~~~

../node_modules/bun-types/fetch.d.ts:36:5 - error TS2403: Subsequent variable declarations must have the same type.  Variable 'Headers' must be of type 'typeof Headers', but here has type '{ new (init?: HeadersInit | undefined): Headers; prototype: Headers; }'.

36 var Headers: {
       ~~~~~~~

  node_modules/@types/node/globals.d.ts:377:13
    377 declare var Headers: typeof globalThis extends {
                    ~~~~~~~
    'Headers' was also declared here.

../node_modules/bun-types/fetch.d.ts:45:5 - error TS2403: Subsequent variable declarations must have the same type.  Variable 'Request' must be of type 'typeof Request', but here has type '{ new (requestInfo: string, requestInit?: RequestInit | undefined): Request; new (requestInfo: RequestInit & { url: string; }): Request; new (requestInfo: Request, requestInit?: RequestInit | undefined): Request; prototype: Request; }'.

45 var Request: {
       ~~~~~~~

  node_modules/@types/node/globals.d.ts:356:13
    356 declare var Request: typeof globalThis extends {
                    ~~~~~~~
    'Request' was also declared here.

../node_modules/bun-types/fetch.d.ts:52:5 - error TS2403: Subsequent variable declarations must have the same type.  Variable 'Response' must be of type 'typeof Response', but here has type '{ new (body?: BodyInit | null | undefined, init?: ResponseInit | undefined): Response; json(body?: any, options?: number | ResponseInit | undefined): Response; redirect(url: string, status?: number | undefined): Response; redirect(url: string, options?: ResponseInit | undefined): Response; error(): Response; }'.

52 var Response: {
       ~~~~~~~~

  node_modules/@types/node/globals.d.ts:363:13
    363 declare var Response: typeof globalThis extends {
                    ~~~~~~~~
    'Response' was also declared here.

../node_modules/bun-types/fetch.d.ts:133:5 - error TS2300: Duplicate identifier 'fetch'.

133 var fetch: {
        ~~~~~

  node_modules/@types/node/globals.d.ts:350:18
    350 declare function fetch(
                         ~~~~~
    'fetch' was also declared here.

node_modules/@types/node/globals.d.ts:348:11 - error TS2320: Interface 'RequestInit' cannot simultaneously extend types 'RequestInit' and 'RequestInit'.
  Named property 'dispatcher' of types 'RequestInit' and 'RequestInit' are not identical.

348 interface RequestInit extends NodeJS.fetch._RequestInit {}
              ~~~~~~~~~~~

node_modules/@types/node/globals.d.ts:348:11 - error TS2320: Interface 'RequestInit' cannot simultaneously extend types 'RequestInit' and 'RequestInit'.
  Named property 'headers' of types 'RequestInit' and 'RequestInit' are not identical.

348 interface RequestInit extends NodeJS.fetch._RequestInit {}
              ~~~~~~~~~~~

node_modules/@types/node/globals.d.ts:348:11 - error TS2320: Interface 'RequestInit' cannot simultaneously extend types 'RequestInit' and 'RequestInit'.
  Named property 'signal' of types 'RequestInit' and 'RequestInit' are not identical.

348 interface RequestInit extends NodeJS.fetch._RequestInit {}
              ~~~~~~~~~~~

node_modules/@types/node/globals.d.ts:350:18 - error TS2300: Duplicate identifier 'fetch'.

350 declare function fetch(
                     ~~~~~

  ../node_modules/bun-types/fetch.d.ts:133:5
    133 var fetch: {
            ~~~~~
    'fetch' was also declared here.

node_modules/@types/node/dom-events.d.ts:116:15 - error TS2320: Interface 'EventTarget' cannot simultaneously extend types '{ addEventListener(type: string, listener: EventListener | EventListenerObject, options?: boolean | AddEventListenerOptions | undefined): void; dispatchEvent(event: Event): boolean; removeEventListener(type: string, listener: EventListener | EventListenerObject, options?: boolean | ... 1 more ... | undefined): void; }' and '_EventTarget'.
  Named property 'addEventListener' of types '{ addEventListener(type: string, listener: EventListener | EventListenerObject, options?: boolean | AddEventListenerOptions | undefined): void; dispatchEvent(event: Event): boolean; removeEventListener(type: string, listener: EventListener | EventListenerObject, options?: boolean | ... 1 more ... | undefined): void; }' and '_EventTarget' are not identical.

116     interface EventTarget extends __EventTarget {}
                  ~~~~~~~~~~~

../node_modules/bun-types/bun.d.ts:1:52 - error TS2304: Cannot find name 'ShellOutput'.

1 declare class _ShellError extends Error implements ShellOutput {
                                                     ~~~~~~~~~~~

../node_modules/bun-types/bun.d.ts:4924:30 - error TS2344: Type '"routes"' does not satisfy the constraint '"error" | "id" | "fetch" | "maxRequestBodySize" | "development"'.

4924    | (DistributedOmit<Serve, "routes"> & {
                                  ~~~~~~~~

../node_modules/bun-types/globals.d.ts:746:6 - error TS2502: 'File' is referenced directly or indirectly in its own type annotation.

746  var File: typeof File;
         ~~~~

../node_modules/bun-types/fetch.d.ts:36:1 - error TS1046: Top-level declarations in .d.ts files must start with either a 'declare' or 'export' modifier.

36 var Headers: {
   ~~~

../node_modules/bun-types/fetch.d.ts:36:5 - error TS2403: Subsequent variable declarations must have the same type.  Variable 'Headers' must be of type 'typeof Headers', but here has type '{ new (init?: HeadersInit | undefined): Headers; prototype: Headers; }'.

36 var Headers: {
       ~~~~~~~

  node_modules/@types/node/globals.d.ts:377:13
    377 declare var Headers: typeof globalThis extends {
                    ~~~~~~~
    'Headers' was also declared here.

../node_modules/bun-types/fetch.d.ts:45:5 - error TS2403: Subsequent variable declarations must have the same type.  Variable 'Request' must be of type 'typeof Request', but here has type '{ new (requestInfo: string, requestInit?: RequestInit | undefined): Request; new (requestInfo: RequestInit & { url: string; }): Request; new (requestInfo: Request, requestInit?: RequestInit | undefined): Request; prototype: Request; }'.

45 var Request: {
       ~~~~~~~

  node_modules/@types/node/globals.d.ts:356:13
    356 declare var Request: typeof globalThis extends {
                    ~~~~~~~
    'Request' was also declared here.

../node_modules/bun-types/fetch.d.ts:52:5 - error TS2403: Subsequent variable declarations must have the same type.  Variable 'Response' must be of type 'typeof Response', but here has type '{ new (body?: BodyInit | null | undefined, init?: ResponseInit | undefined): Response; json(body?: any, options?: number | ResponseInit | undefined): Response; redirect(url: string, status?: number | undefined): Response; redirect(url: string, options?: ResponseInit | undefined): Response; error(): Response; }'.

52 var Response: {
       ~~~~~~~~

  node_modules/@types/node/globals.d.ts:363:13
    363 declare var Response: typeof globalThis extends {
                    ~~~~~~~~
    'Response' was also declared here.

../node_modules/bun-types/fetch.d.ts:133:5 - error TS2300: Duplicate identifier 'fetch'.

133 var fetch: {
        ~~~~~

  node_modules/@types/node/globals.d.ts:350:18
    350 declare function fetch(
                         ~~~~~
    'fetch' was also declared here.


Found 26 errors.

[dbaeumer]

Your environment somehow looks of. The repository should be self contained and the ESLint extension is not using any bun-types. Somehow they seem to be present in the parent directory and used. Could you try to delete that node_modules folder?

[cowboyd]

@dbaeumer Nice catch! I totally missed the ../. Getting rid of that rogue node_modules/ directory worked.

[SCWells72]

Did you ever get past this error? I'm trying to use this language server with another client (LSP4IJ), and I'm seeing the exact same error. I don't know if I need to raise an issue with LSP4IJ to ensure it sends over a working directory somehow, or if there's a configuration change required, or what. Interested to know if you've been able to get this working with eglot (or any other non-VS Code client).

[cowboyd]

@SCWells72 I wasn't able to get close by looking at how the nvim language server handled it, but I never got it quite working

[angelozerr]

@dbaeumer @cowboyd @SCWells72 for your information I have integrated (basicly) eslint language server inside IntelliJ with LSP4IJ

See https://github.com/redhat-developer/lsp4ij/blob/main/docs/user-defined-ls/vscode-eslint-language-server.md

To avoid the original error, the fix was to send the following configuration to the eslint language server:

{
  "validate": "on",
  "packageManager": "npm",
  "useESLintClass": false,
  "experimental": {
    "useFlatConfig": false
  },
  "codeActionOnSave": {
    "mode": "all"
  },
  "format": false,
  "quiet": false,
  "onIgnoredFiles": "off",
  "options": {},
  "rulesCustomizations": [],
  "run": "onType",
  "problems": {
    "shortenToSingleLine": false
  },
  "nodePath": "",
  "codeAction": {
    "disableRuleComment": {
      "enable": true,
      "location": "separateLine",
      "commentStyle": "line"
    },
    "showDocumentation": {
      "enable": true
    }
  }
}

The important config is "nodePath": "", and not "nodePath": null, which is the default value.

This integration of eslint was done with zero code, just with declarative mean, see JSON descriptors at https://github.com/redhat-developer/lsp4ij/tree/main/src/main/resources/templates/lsp/vscode-eslint-language-server

This config auto-install eslint language server with this installer https://github.com/redhat-developer/lsp4ij/blob/05c06d3e156530e2c45d58aacb3fd03358f513df/src/main/resources/templates/lsp/vscode-eslint-language-server/installer.json#L21

npm install vscode-langservers-extracted --force

The integration of eslint language server inside IntelliJ doesn't provide the full features like vscode-eslint because the language server is not full compliant compatible with LSP:

• client register custom file watcher

  vscode-eslint/client/src/client.ts

  Line 426 in c7c2ebf

  Workspace.createFileSystemWatcher('**/.eslintr{c.js,c.cjs,c.yaml,c.yml,c,c.json}'),

  those file watcher should be declared on server side.
• client manages pull diagnostics of focus

  vscode-eslint/client/src/client.ts

  Line 451 in c7c2ebf

  onFocus: true,

  , LSP doesn't provides this capability. Perhaps LSP should specifiy textDocument/didFocus because I have see that for language server wich manages AI.
• other?

@dbaeumer it would be more cleaner to provide an npm module for eslint (instead of using the vscode-langservers-extracted) and manage most features with LSP server.

Do you think you could add in your README, LSP client which integrates your LSP eslint language server? If you are OK I could create a PR to add LSP4IJ.

[SCWells72]

@angelozerr, the ESLint integration seems to working very well to me. I've made a few changes in my own plugin to accommodate it, specifically to disable another, slower ESLint integration (via Salesforce Code Analyzer 5) if that language server is installed/started. Combined with the TypeScript language server, this provides a really nice, complete set of static code analysis capabilities for JavaScript and TypeScript in Community Edition IDEs. Thanks so much!