neoclide/coc.nvim · error · Error

Illegal argument: pattern

Error message

Illegal argument: pattern

What it means

RelativePattern requires the pattern argument to be a string glob; passing any other type throws illegalArgument('pattern') with message "Illegal argument: pattern". This check runs after base validation in the constructor.

Source

Thrown at src/model/relativePattern.ts:17

'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,
      baseUri: this.baseUri.toJSON()
    }
  }
}

View on GitHub (pinned to 50e974d969)

Solutions

1. Pass a glob string such as '**/*.ts'.
2. Coalesce config values with a default: pattern ?? '**/*'.
3. Convert RegExp or array inputs to a string (join array patterns with commas or build multiple RelativePatterns).
4. Validate typeof pattern === 'string' before constructing.

Example fix

// before
new RelativePattern(folder, config.exclude) // array | undefined
// after
new RelativePattern(folder, Array.isArray(config.exclude) ? config.exclude.join(',') : (config.exclude ?? '**/*'))

if (typeof pattern !== 'string') throw new Error('RelativePattern pattern must be a glob string')

function isGlob(v: unknown): v is string { return typeof v === 'string' }

try { const rp = new RelativePattern(base, pattern) } catch (e) { if (String(e).includes('Illegal argument: pattern')) { const rp = new RelativePattern(base, String(pattern ?? '**/*')) } else throw e }

When it happens

Trigger: new RelativePattern(base, someVar) where someVar is undefined, null, a RegExp, or an array of globs.

Common situations: Reading the glob from config where the key is missing (undefined); passing a RegExp instead of a glob string; arrays of patterns from settings not being joined into one string.

Related errors

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

AI-assisted analysis of neoclide/coc.nvim@50e974d969 (2026-08-31). Data as JSON: /api/errors/2bf557a873fa8d04. Report an issue: GitHub.