undefined[] converted to any[] in JS

[DanielRosenwasser]

I found related broken example.

Version 4.3.0-dev.20210228

/** @type {() => undefined} */
function a () { return undefined }

// Actually: any
// Expected: undefined
const b = a()

Originally posted by @awerlogus in #42133 (comment)

[DanielRosenwasser]

We need a complete repro, including compiler options.

[awerlogus]

{
    "compilerOptions": {
      "alwaysStrict": true,
      "keyofStringsOnly": true,
      "noUncheckedIndexedAccess": true,
      "noFallthroughCasesInSwitch": true,
      "downlevelIteration": true,
      "allowUnreachableCode": false,
      "skipLibCheck": true,
      "module": "es6",
      "moduleResolution": "node",
      "declaration": false,
      "removeComments": true,
      "emitDecoratorMetadata": true,
      "esModuleInterop": true,
      "experimentalDecorators": true,
      "noErrorTruncation": true,
      "noUnusedParameters": true,
      "target": "ESNext",
      "sourceMap": false,
      "baseUrl": "./src",
      "incremental": false,
      "strict": true,
      "checkJs": true,
      "allowJs": true,
      "noEmit": true
    },
    "exclude":[
      "node_modules"
    ]
  }