noImplicitReturns misidentifies generator return as function return when strictNullChecks is false

[trxcllnt]

TypeScript Version: 2.6.1 - 2.7.0-dev.20171128

Code:

// index.ts
function* testGenerator() {
    if (Math.random() > 0.5) {
        return;
    }
    yield 'hello';
}

/* tsconfig.json
{
    "files": ["index.ts"],
    "compilerOptions": {
        "lib": ["esnext"], "target": "ESNEXT", "module": "es2015",
        "strictNullChecks": true,
        "noImplicitReturns": true
    }
}
*/

Expected behavior:

No errors due to the generator's early return, regardless of whether strictNullChecks is true or false.

Actual behavior:

• No errors when strictNullChecks is true
• The following error when strictNullChecks is false:
  index.ts(3,9): error TS7030: Not all code paths return a value.

[mhegazy]

PRs welcomed!

[mhegazy]

thanks @Kingwl !

[trxcllnt]

@mhegazy @Kingwl thanks! I haven't tested, but this issue may affect async generators also. If so, would the fix in the PR will also fix them?

[Kingwl]

@trxcllnt sure