Error: spawn wslvar ENOENT when using create-snowpack-app on WSL2

[TedChenNZ]

When I run 'npm start' on WSL 2 (Ubuntu 18.04, node v12.18.4 and v14.11.0) I get:

[snowpack] (node:5485) UnhandledPromiseRejectionWarning: Error: spawn wslvar ENOENT
    at Process.ChildProcess._handle.onexit (internal/child_process.js:268:19)
    at onErrorNT (internal/child_process.js:464:16)
    at processTicksAndRejections (internal/process/task_queues.js:80:21)
(Use `node --trace-warnings ...` to show where the warning was created)
[snowpack] (node:5485) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
[snowpack] (node:5485) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

Steps to Reproduce

npx create-snowpack-app new-dir --template @snowpack/app-template-react-typescript
cd new-dir
npm start

Note: I have tried this in the home ~ directory so it should be within the linux file system.

I've tried this for both @snowpack/app-template-react-typescript and @snowpack/app-template-react and I get the same error.

I'm not entirely sure what the consequences for the error are, I can still load the dev server and live reloading seems to work.

[FredKSchott]

I'm sorry, I can't reproduce on my machine and can't debug without more information (it seems like a promise is failing, but hard to say which one. If you can find out which is failing and why, we could add a better error message here).

This issue might also be relevant: facebook/create-react-app#7251

[TedChenNZ]

While running npm run start -- --verbose I get the following :

snowpack

  http://localhost:8080
  Server started in 54ms.

▼ Console

[snowpack] run command: dev
[snowpack] loaded plugin: @snowpack/plugin-react-refresh
[snowpack] loaded plugin: @snowpack/plugin-dotenv
[snowpack] loaded plugin: @snowpack/plugin-typescript
[snowpack] config loaded: {
  exclude: [
    '**/node_modules/**/*',
    '**/.types/**/*',
    '/home/ted/new-dir/build/**/*',
    '__tests__/**/*',
    '**/*.@(spec|test).*'
  ],
  plugins: [
    {
      name: '@snowpack/plugin-esbuild',
      resolve: [Object],
      load: [AsyncFunction: load],
      cleanup: [Function: cleanup]
    },
    {
      name: '@snowpack/plugin-react-refresh',
      transform: [Function: transform]
    },
    { name: '@snowpack/plugin-dotenv' },
    { name: '@snowpack/plugin-typescript', run: [AsyncFunction: run] }
  ],
  alias: {},
  scripts: {},
  installOptions: { rollup: { plugins: [] } },
  devOptions: {
    secure: false,
    hostname: 'localhost',
    port: 8080,
    open: 'default',
    out: '/home/ted/new-dir/build',
    output: 'dashboard',
    fallback: 'index.html',
    hmrDelay: 0,
    hmrPort: 12321
  },
  buildOptions: {
    baseUrl: '/',
    webModulesUrl: '/web_modules',
    clean: false,
    metaDir: '__snowpack__',
    minify: false,
    sourceMaps: false,
    watch: false
  },
  experiments: { ssr: false },
  webDependencies: undefined,
  mount: {
    '/home/ted/new-dir/public': '/',
    '/home/ted/new-dir/src': '/_dist_'
  },
  knownEntrypoints: [],
  proxy: [],
  _extensionMap: { '.mjs': '.js', '.jsx': '.js', '.ts': '.js', '.tsx': '.js' }
}
[snowpack] lockfile not loaded
[snowpack] Using cache folder: node_modules/.cache/snowpack/dev
[snowpack] Cache up-to-date. Using existing cache
[snowpack] (node:223) UnhandledPromiseRejectionWarning: Error: spawn wslvar ENOENT
    at Process.ChildProcess._handle.onexit (internal/child_process.js:267:19)
    at onErrorNT (internal/child_process.js:469:16)
    at processTicksAndRejections (internal/process/task_queues.js:84:21)
[snowpack] (node:223) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
[snowpack] (node:223) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

▼ @snowpack/plugin-typescript

  9:42:31 AM - Starting compilation in watch mode...


  9:42:36 AM - Found 0 errors. Watching for file changes.

Hopefully that helps narrow it down?

[FredKSchott]

That does, actually. It's interesting that @snowpack/plugin-typescript is clearly able to spawn the tsc typescript CLI just fine. Maybe it's esbuild that's dying. What version of Node.js are you running?

[TedChenNZ]

I'm using v12.18.4

I also just tried this on a different machine with a fresh windows and wsl2 build and it worked fine there without errors. The new machine also gets my browser to open up localhost, whereas the old machine doesn't.

I'm not super familiar with how snowpack works, but I would assume esbuild was working since it still managed to build fine and I could open localhost and see live reloading work.

I'm thinking it might be erroring on opening up localhost in the browser (similar to the issue in the link you provided)? It might be something to do with my old machine using the Window Insider Beta channel, and wsl2 being installed through that from before wsl2 was released to non-insider builds of windows.

[littlebtc]

It seems to be the problem caused by open@7.3.0.

sindresorhus/open#198

Basically you need wslu installed and powershell.exe in PATH to properly open browser from WSL 2.

[TedChenNZ]

This totally fixed it. Thanks!

[FredKSchott]

Nice! How common is this issue? Would love to add a more helpful error if possible

[tmueller]

As a workaround, open in devOptions can be set to "none" as shown here. This prevents the codepath, throwing the Error, from being executed.

[FredKSchott]

Great, added a better warning in c890042 (actually we just ignore this now, giving you that "none" fallback behavior by default).