Before You File a Proposal Please Confirm You Have Done The Following...

• I have searched for related issues and found none that match my proposal.
• I have searched the current rule list and found no rules that match my proposal.
• I have read the FAQ and my problem is not listed.

My proposal is suitable for this project

• I believe my proposal would be useful to the broader TypeScript community (meaning it is not a niche proposal).

Link to the rule's documentation

https://typescript-eslint.io/rules/only-throw-error

Description

only-throw-error (and prefer-promise-reject-errors) disallow throwing non-error values. only-throw-error (and with #10375 prefer-promise-reject-errors too) can be configured to allow throwing unknown and any types in addition to error values.

It's necessary to enable allowThrowingUnknown so re-throwing a cached error is valid (or any in some tsconfig.json configurations):

function test() {
  try {
    // ...
  } catch (error) {
    if (x) {
      throw new Error()
    }

    // this would otherwise fail
    throw error;
  }
}

While configuring allowThrowingUnknown makes the above pass, it allows potentially unsafe throwing of an unknown type:

function foo(): unknown {
  // not necessarily returns an `Error` object
}

function test() {
  // this should fail
  throw foo();
}

This issue proposes an additional option, a stricter form of allowThrowingUnknown, which will allow re-throwing a caught error.

This is relevant both to only-throw-error and prefer-promise-reject-errors.

Fail

function foo(): unknown {
  // not necessarily returns an `Error` object
}

function test() {
  // this should fail
  throw foo();
}

Pass

function test() {
  try {
    // ...
  } catch (error) {
    if (x) {
      throw new Error()
    }

    throw error;
  }
}

Additional Info

No response