$RefreshReg$ is not defined in web worker after upgrading to 9.4.0

Bug report

I believe this is a React Refresh-related issue.

Potentially relevant:

• https://github.com/facebook/react-native/issues/25684
• https://github.com/facebook/react/blob/master/packages/react-refresh/src/__tests__/ReactFresh-test.js

Describe the bug

After upgrading to Next.js 9.4.0, workers throw the following exception on load:

Uncaught ReferenceError: $RefreshReg$ is not defined
    at Module.eval (blocks.ts:239)
    at eval (blocks.ts:296)
    at Module../shared/blocks.ts (48ba4b417edc794a158b.worker.js:311)
    at __webpack_require__ (48ba4b417edc794a158b.worker.js:29)
    at Module.eval (WorldChunk.ts:12)
    at eval (WorldChunk.ts?c4f7:22)
    at Module../lib/Data/WorldChunk.ts (48ba4b417edc794a158b.worker.js:115)
    at __webpack_require__ (48ba4b417edc794a158b.worker.js:29)
    at Module.eval (WorldChunkReader.worker.ts?024a:1)
    at eval (WorldChunkReader.worker.ts?024a:21)

To Reproduce

1. Configure worker-loader like so in next.config.js:

config.module.rules.unshift({
  test: /\.worker\.(js|ts|tsx)$/,
  loader: "worker-loader",
  options: {
    name: "static/[hash].worker.js",
    publicPath: "/_next/",
  },
});

// Overcome webpack referencing `window` in chunks
config.output.globalObject = "self";

1. Load a worker
2. See error

Expected behavior

No error, workers load successfully as in Next 9.3

Screenshots

System information

• OS: macOS
• Browser (if applies) Chrome
• Version of Next.js: 9.4.0
• Version of Node.js: 13.12.0

[Jarred-Sumner]

@Timer here you go: https://github.com/Jarred-Sumner/repro-refreshregistry

[hbeckeri]

I began seeing this same issue when I upgraded to next 9.4 from 9.3. It’s only impacting dev for me, when I deployed it to vercel, the error was not there