Does not handle TypeScript file as worker source

[Alex-D]

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Describe the bug

Vite does not handle TypeScript file as worker source.

Error: Invalid loader: "ts?worker&inline" (valid: js, jsx, ts, tsx, css, json, text, base64, dataurl, file, binary)

Reproduction

• Start with https://github.com/vitejs/vite/tree/main/packages/playground/worker
• Rename my-worker.js to my-worker.ts
• Add (or not) the lang="ts" to index.html script tag
• yarn dev
• Get the error

System Info

• vite version: 2.0.0-beta.8
• Operating System: WSL on Windows 10
• Node version: 14.4.0
• Package manager (npm/yarn/pnpm) and version: yarn 1.22.5 / npm 6.14.10

Logs (Optional if provided reproduction)

vite:esbuild esbuild error with options used:  {
  loader: 'ts?worker&inline',
  sourcemap: true,
  sourcefile: '/c/dev/vite/packages/playground/worker/my-worker.ts?worker&inline'
}
[vite] Internal server error:
  Plugin: vite:esbuild
  File: /c/dev/vite/packages/playground/worker/my-worker.ts?worker&inline
  Error: Invalid loader: "ts?worker&inline" (valid: js, jsx, ts, tsx, css, json, text, base64, dataurl, file, binary)
      at /c/dev/vite/node_modules/esbuild/lib/main.js:843:33
      at handleIncomingPacket (/c/dev/vite/node_modules/esbuild/lib/main.js:563:9)
      at Socket.readFromStdout (/c/dev/vite/node_modules/esbuild/lib/main.js:481:7)
      at Socket.emit (events.js:315:20)
      at addChunk (_stream_readable.js:302:12)
      at readableAddChunk (_stream_readable.js:278:9)
      at Socket.Readable.push (_stream_readable.js:217:10)
      at Pipe.onStreamRead (internal/stream_base_commons.js:186:23)
vite:time 64ms  /my-worker.ts?worker&inline +65ms

vite:esbuild esbuild error with options used:  {
  loader: 'ts?worker',
  sourcemap: true,
  sourcefile: '/c/dev/vite/packages/playground/worker/my-worker.ts?worker'
} +37ms
[vite] Internal server error:
  Plugin: vite:esbuild
  File: /c/dev/vite/packages/playground/worker/my-worker.ts?worker
  Error: Invalid loader: "ts?worker" (valid: js, jsx, ts, tsx, css, json, text, base64, dataurl, file, binary)
      at /c/dev/vite/node_modules/esbuild/lib/main.js:843:33
      at handleIncomingPacket (/c/dev/vite/node_modules/esbuild/lib/main.js:563:9)
      at Socket.readFromStdout (/c/dev/vite/node_modules/esbuild/lib/main.js:481:7)
      at Socket.emit (events.js:315:20)
      at addChunk (_stream_readable.js:302:12)
      at readableAddChunk (_stream_readable.js:278:9)
      at Socket.Readable.push (_stream_readable.js:217:10)
      at Pipe.onStreamRead (internal/stream_base_commons.js:186:23)
  vite:time 71ms  /my-worker.ts?worker +11ms