Handling of JavaScript errors in ObjectInfo's callback

[mhofman]

It looks like errors thrown by ObjectInfo's callback cannot be caught in process' "uncaughtException" event.

What's even more surprising is that the error is subsequently thrown the next time an ObjectInfo is constructed.

The workaround is to wrap the callback into a setImmediate call, but that shouldn't be necessary since the native side already does that.

I have a feeling this is an issue for https://github.com/node-ffi-napi/setimmediate-napi

From a quick research I guess calling napi_fatal_exception instead of e.ThrowAsJavaScriptException() would do the trick, but I'm probably out of my depth here.

Repro:

const { ObjectInfo, WeakTag } = require("@mhofman/weak-napi-native");

const map = new WeakMap();

async function test(call) {
    let listener;

    const thrown = new Promise(resolve => {
        listener = error => void resolve(error);
        process.on("uncaughtException", listener);
    });

    let object = {};
    const info = new ObjectInfo(object, () => {
        call(() => {
            throw new Error(
                "I should be able to get this in uncaughtException"
            );
        });
    });

    map.set(object, new WeakTag(info));

    object = undefined;
    await Promise.resolve(resolve => setImmediate(resolve));
    gc();

    const result = await Promise.race([
        thrown,
        new Promise(resolve => setTimeout(resolve, 200, "Bailing")),
    ]);

    process.removeListener("uncaughtException", listener);

    return result;
}

(async () => {
    console.log("setImmediate start");
    console.log(
        "setImmediate",
        await test(fn => {
            console.log("setImmediate callback invoked");
            setImmediate(fn);
        })
    );

    console.log("direct start");
    console.log(
        "direct",
        await test(fn => {
            console.log("direct callback invoked");
            fn();
        })
    );

    try {
        const info = new ObjectInfo({}, () => {});
    } catch (error) {
        console.log("Caught error on construct", error);
    }

    console.log("done");

    process.exit();
})();

Output:

setImmediate start
setImmediate callback invoked
setImmediate Error: I should be able to get this in uncaughtException
direct start
direct callback invoked
direct Bailing
Caught error on construct Error: I should be able to get this in uncaughtException
done