Before You File a Bug Report Please Confirm You Have Done The Following...

• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.
• I have searched for related issues and found none that matched my issue.
• I have read the FAQ and my problem is not listed.

Playground Link

https://typescript-eslint.io/play/#ts=4.8.3&sourceType=module&code=KYDwDg9gTgLgBAMwK4DsDGMCWEVwEYAUAlAFxwAKUEAtpgM7AA8AbhJgCYB8AsAFCiRYiVBmy5CAQzJ4IEADbAJKUnFYc+A6PGTosOfAQkB+abIVKVlGvSZqucAD6q27OAG8+cOJgRxDcAF4AuBQkOTkiOChgGCQoXCtaBgA6aIArYAwCFGAAdzgAUSgqKGIiTzgYAAsqfJz8opLiPgBfPiA&eslintrc=N4KABGBEBOCuA2BTAzpAXGUEKQAIBcBPABxQGNoBLY-AWhXkoDt8B6Y6AewFtLlFaAM1hMy+Spya0AhskKj0URNC7RI4MAF8QmoA&tsconfig=N4KABGBEDGD2C2AHAlgGwKYCcDyiAuysAdgM6QBcYoEEkJemy0eAcgK6qoDCAFutAGsylBm3TgwAXxCSgA

Repro Code

export function b(): Promise<void>
export function b(a: boolean): void
export function b(a?: boolean): Promise<void> | void {
  if (a == null) return Promise.reject(new Error())
  throw new Error()
}

ESLint Config

module.exports = {
  parser: "@typescript-eslint/parser",
  rules: {
    "@typescript-eslint/promise-function-async": "error",
  },
};

tsconfig

{
  "compilerOptions": {
    // ...
  }
}

Expected Result

No error.

Actual Result

Error.

Additional Info

Error will disappear if swap line 1 and line 2.

Versions