yamadashy/repomix · error

Failed to load language ${langName}: ${message}

Error message

Failed to load language ${langName}: ${message}

What it means

loadLanguage resolves the per-language .wasm grammar file and loads it via Language.load. Any failure (resolution or load) is wrapped as 'Failed to load language <name>: <message>'. This is a plain Error, not RepomixError, and is later re-wrapped by prepareLang.

Source

Thrown at src/core/treeSitter/loadLanguage.ts:40

/**
 * Get the WASM base path from environment variable or custom setting.
 */
function getWasmBasePath(): string | null {
  return customWasmBasePath ?? process.env.REPOMIX_WASM_DIR ?? null;
}

export async function loadLanguage(langName: string): Promise<Language> {
  if (!langName) {
    throw new Error('Invalid language name');
  }

  try {
    const wasmPath = await getWasmPath(langName);
    return await Language.load(wasmPath);
  } catch (error: unknown) {
    const message = error instanceof Error ? error.message : String(error);
    throw new Error(`Failed to load language ${langName}: ${message}`);
  }
}

async function getWasmPath(langName: string): Promise<string> {
  const wasmBasePath = getWasmBasePath();

  let wasmPath: string;
  if (wasmBasePath) {
    // Use custom WASM path for bundled environments
    wasmPath = path.join(wasmBasePath, `tree-sitter-${langName}.wasm`);
  } else {
    // Use require.resolve for standard node_modules environments
    wasmPath = require.resolve(`@repomix/tree-sitter-wasms/out/tree-sitter-${langName}.wasm`);
  }

  try {
    await fs.access(wasmPath);
    return wasmPath;

View on GitHub (pinned to f465ad9093)

Solutions

1. Check the inlined message and verify the wasm path exists (ls the wasm base dir)
2. Reinstall tree-sitter-wasms / node_modules to restore grammar files
3. Point the wasm base path to a directory containing the required grammar wasms
4. Rebuild grammars for the installed web-tree-sitter ABI if versions mismatch

Example fix

// before
getWasmBasePath = () => '/custom/stale-wasms';
// after
getWasmBasePath = () => path.dirname(require.resolve('tree-sitter-wasms/out/tree-sitter-typescript.wasm'));

import { access, constants } from 'node:fs/promises';
import path from 'node:path';
const wasmPath = path.join(getWasmBasePath(), `tree-sitter-${langName}.wasm`);
try { await access(wasmPath, constants.R_OK); }
catch { throw new Error(`grammar wasm missing: ${wasmPath}`); }

try {
  const lang = await loadLanguage('python');
} catch (err) {
  if (String(err.message).startsWith('Failed to load language')) {
    console.error('grammar wasm missing/incompatible — reinstall tree-sitter-wasms');
  } else throw err;
}

When it happens

Trigger: getWasmPath returns a path whose file is missing or unreadable, or Language.load fails on a corrupt/incompatible wasm (e.g. grammar built for a different tree-sitter ABI version).

Common situations: Partial npm install skipping optional tree-sitter-wasms artifacts; custom getWasmBasePath pointing to a directory that lacks the language wasm; upgraded web-tree-sitter with stale grammar wasms.

Related errors

• Failed to prepare language ${name}: ${message}
• Failed to initialize parser: ${message}
• WASM file not found for language ${langName}: ${wasmPath}
• Language configuration not found for: ${name}
• Failed to compress ${filePath}, using uncompressed content:

AI-assisted analysis of yamadashy/repomix@f465ad9093 (2026-08-29). Data as JSON: /api/errors/f7a9aaee46fb0a8c. Report an issue: GitHub.