neoclide/coc.nvim · error · Error

Illegal argument: base

Error message

Illegal argument: base

What it means

The RelativePattern constructor validates its base argument: it must be a plain string path, a URI instance, or an object with a string .uri property (a WorkspaceFolder). Anything else (null, undefined, a plain object without uri) triggers illegalArgument('base'), reported as "Illegal argument: base".

Source

Thrown at src/model/relativePattern.ts:13

'use strict'
import { URI } from 'vscode-uri'
import { illegalArgument } from '../util/errors'
import { WorkspaceFolder } from 'vscode-languageserver-types'

export default class RelativePattern {
  public pattern: string
  public baseUri: URI

  constructor(base: WorkspaceFolder | URI | string, pattern: string) {
    if (typeof base !== 'string') {
      if (!base || !URI.isUri(base) && typeof base.uri !== 'string') {
        throw illegalArgument('base')
      }
    }
    if (typeof pattern !== 'string') {
      throw illegalArgument('pattern')
    }
    if (typeof base === 'string') {
      this.baseUri = URI.file(base)
    } else if (URI.isUri(base)) {
      this.baseUri = base
    } else {
      this.baseUri = URI.parse(base.uri)
    }
    this.pattern = pattern
  }

  public toJSON() {
    return {
      pattern: this.pattern,

View on GitHub (pinned to 50e974d969)

Solutions

1. Pass a string path, a proper URI (workspace.createFileRangeUri/Uri.file), or a real WorkspaceFolder.
2. Guard base for null/undefined before constructing the pattern.
3. Ensure the object's .uri is a string; convert URI objects to strings with .toString() if needed.
4. Avoid mixing Uri implementations from different module copies.

Example fix

// before
const rp = new RelativePattern(maybeFolder, '**/*.ts')
// after
if (maybeFolder && (typeof maybeFolder === 'string' || typeof maybeFolder.uri === 'string')) {
  const rp = new RelativePattern(maybeFolder, '**/*.ts')
}

if (!(typeof base === 'string' || (base && typeof base.uri === 'string'))) throw new Error('RelativePattern base must be a string or folder-like')

function isRelativePatternBase(v: unknown): v is string | { uri: string } {
  return typeof v === 'string' || (!!v && typeof (v as any).uri === 'string')
}

try { const rp = new RelativePattern(base, glob) } catch (e) { if (String(e).includes('Illegal argument: base')) { /* normalize base to Uri.file(...) and retry */ } else throw e }

When it happens

Trigger: new RelativePattern(undefined, '**/*.ts'), passing a WorkspaceFolder-like object whose uri is not a string, or passing a null base.

Common situations: Destructuring a workspace folder before it is assigned; using a vscode.Uri from a different coc/vscode module instance so URI.isUri fails and the .uri fallback also misses; copying code from VS Code API where base types differ.

Related errors

• Illegal argument: pattern
• folder should be string
• watchman not found

AI-assisted analysis of neoclide/coc.nvim@50e974d969 (2026-08-31). Data as JSON: /api/errors/56e33760b39d06f7. Report an issue: GitHub.