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=5.4.5&fileType=.ts&code=GYVwdgxgLglg9mABMAjAHgCoD4AUBKRAbwChFEAbAUykUoCc6AuRABTrgFsYBnSzLANylEUABbsA7rQZCAvsWKhIsBMgBMmFABpEGNbgIkyVGvSat2XXpqyIAPhc48%2BewcLGTpdOUA&eslintrc=N4KABGBEBOCuA2BTAzpAXGUEKQAIBcBPABxQGNoBLY-AWhXkoDt8B6AeyfkNvwAto7AO71og6OjABtcNhyIx7CQBpZcrHOyQAhvHjDJMzZsgAFQQFtKyRJDWaAuvYgBfe09cgXQA&tsconfig=&tokens=false

Repro Code

function f1<T>() {
  let err: Promise<T>;
  throw err;
}

function f2<T1, T2>() {
  let err: Promise<T1> | Promise<T2>;
  throw err;
}

ESLint Config

{
  "rules": {
    "@typescript-eslint/only-throw-error": [
      "error",
      {
        "allow": [
          "Promise"
        ]
      }
    ]
  }
}

tsconfig

Expected Result

The only-throw-error warning should not be triggered by f1() or f2(). When the "allow" option is Promise, I should be able to throw an error of Promise<A> | Promise<B>.

Actual Result

The "only-throw-error" rule triggers when a union is thrown.

Expected an error object to be thrown. 8:9 - 8:12

Additional Info

My actual use-case is with TanStack Router, which allows users to throw redirect(...) (this throws a Redirect type). I have a function that can return various redirects (which are later thrown):

function getRedirect(a, b) {
    if (a) return redirect(...); // returns Redirect<A>
    else return redirect(...); // returns Redirect<B>
}

This returns a union of Redirect<A> | Redirect<B>. The following code triggers and ESLint error because it is trying to throw a union type.

throw getRedirect(a, b);