Re-throwing error in transaction catch block will propagate transaction error again

[crazyones110]

Repro

const db = new Dexie("Test_Re_Throw_Error");
db.version(1).stores({
  friends: `
  id,
  name,
  age`,
});
db.transaction("r", ["friends"], generateError).catch(e => {
  /*
  I re-throw transaction error on purpose, in my real code,
  it's like this: throw new CustomError(e)
  for clearer identification
  */
  throw new Error("throw again");
}).catch(e => {
  console.log("outermost error", e);
});

async function generateError() {
  await Promise.reject("inner error");
}

It's weird that throw again error was caught but inner error was exposed unexpectedly.

Dexie Version

3.2.1

[dfahlander]

I copied and pasted your repro into a jsfiddle but I get what was expected, the "throw again" error.

https://jsfiddle.net/nwufgymd/

[crazyones110]

@dfahlander Well, the unhandledrejection seemed to be swallowed by sandbox environment.
I have added an unhandledrejection event handler to illustrate. https://jsfiddle.net/r0hkocL5/
Or you can start your local dev environment to see exactly my screenshot showed.

[dfahlander]

I see. The code behaves as expected in terms of what code paths are visited but the problematic thing is that unhandledrejection gets fired even though you are catching the error. The problem origins from the custom propagation to unhandledrejection that we do for legacy reasons (such as supporting Internet Explorer). I'll see what we can do fix it and whether it would be ok now in Dexie 4.0 to remove that custom propagation of unhandledrejection as it can generate undesired and inaccurate noise in the debugging experience.

Not to self: Check if we can remove our custom unhandledrejection propagation in the promise module and rely on the native unhandledrejection to do its job.