Why does failing to call a callback result in a panic?

[CMCDragonkai]

I have 2 pieces of code here, one of them throws an exception properly, and the other results in a panic.

#[napi]
pub fn throw_error1() -> Result<()> {
  let x: Result<()> = Err(Error::new(Status::InvalidArg, "Manual Error".to_owned()));
  x.or_else(
    |err| {
      return Err(Error::from_reason(err.to_string()));
    }
  )?;
  return Ok(());
}

#[napi]
pub fn throw_error2<T: Fn() -> Result<()>>(
  callback: T
) -> Result<()> {
  callback().or_else(
    |err| Err(Error::from_reason(err.to_string()))
  )?;
  return Ok(());
}

In the second case, if I give it a bad function:

try {
  native.throwError2(
    webcrypto.getRandomValues
  );
} catch (e) {
  console.log(e.message);
}

I get a panic like this:

thread '<unnamed>' panicked at 'Throw error failed, status: [PendingException], raw message: "PendingException, Failed to call napi callback", raw status: [GenericFailure]', /home/cmcdragonkai/.cargo/registry/src/github.com-1ecc6299db9ec823/napi-2.10.1/src/error.rs:322:1
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
fatal runtime error: failed to initiate panic, error 5
Aborted (core dumped)

What makes a callback failure a panic?

[jjangga0214]

You may ought to check this out?
https://napi.rs/docs/concepts/threadsafe-function.en#errorstrategy