Describe the bug

On an existing project that uses parcel, I switched to vite but that results in web workers not working anymore / returning undefined.

Reference issue with the dev verifying that the worker syntax matches vite's expectations:

• Switching bundler to vite instead of parcel breaks web workers gkjohnson/three-gpu-pathtracer#355

Vite worker docs, which use the same syntax as the project at hand:
https://vitejs.dev/guide/features.html#import-with-constructors

My best guess is that the bug here is that a worker is used from a sub-sub package (three-gpu-pathtracer uses the worker from three-mesh-bvh) and that somehow doesn't work in vite right now?

Links to the source code to easily follow the chain until the actual worker:

• https://github.com/gkjohnson/three-gpu-pathtracer/blob/main/example/index.js#L682
  (identical to the index.js in the repro project)
• https://github.com/gkjohnson/three-gpu-pathtracer/blob/main/src/workers/PathTracingSceneWorker.js#LL10C51-L10C51
• https://github.com/gkjohnson/three-mesh-bvh/blob/master/src/workers/GenerateMeshBVHWorker.js#L9
• https://github.com/gkjohnson/three-mesh-bvh/blob/master/src/workers/generateAsync.worker.js
  (the actual worker)

Reproduction

https://stackblitz.com/edit/vitejs-vite-k1ccfw?file=index.js

Steps to reproduce

Steps to reproduce in the StackBlitz project linked above:

• Run npm run dev
• Note page loads
• Note page stops loading and console logs error Uncaught (in promise) Error: GenerateMeshBVHWorker: undefined at worker.onerror

Compare behaviour to https://gkjohnson.github.io/three-gpu-pathtracer/example/bundle/index.html

Steps to reproduce locally:

• fork https://github.com/gkjohnson/three-gpu-pathtracer
• run npm install --save-dev vite
• in package.json, add "start-vite": "cd example && vite --host", in scripts
• run npm run start-vite
• visit the page
• note loading works fine, then the MeshBVH worker returns undefined and logs to the console: Uncaught (in promise) Error: GenerateMeshBVHWorker: undefined

System Info

Reproduces on any system I tried on.

On StackBlitz:

  System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 16.14.2 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 7.17.0 - /usr/local/bin/npm
  npmPackages:
    vite: ^4.0.4 => 4.0.4 

Used Package Manager

npm

Logs

Uncaught (in promise) Error: GenerateMeshBVHWorker: undefined at worker.onerror

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.