[krodak]

Overview

An exported throws(JSException) function that returns a JSObject or a @JS protocol threw ReferenceError: Attempted to use invalid reference 0 in JavaScript instead of the Swift error. The generated glue lifted the return value before it checked tmpRetException, so it read an object id that Swift never returned.

The exception check now runs right after the instance.exports.* call, before the lift:

const ret = instance.exports.bjs_MyViewController_validatedDelegate(this.pointer);
if (tmpRetException) {
    // ...
    throw error;
}
const ret1 = swift.memory.getObject(ret);
swift.memory.release(ret);
return ret1;

The second commit pins the example build jobs to ubuntu-22.04. ubuntu-latest is now 26.04, where apt-get cannot find libgcc-9-dev for the ubuntu2204 toolchain.

Testing

Added a throwing protocol return to the Protocol.swift snapshot input and two runtime tests that throw from a JSObject and a protocol return. Both runtime tests fail without the fix. BridgeJS snapshot tests and make unittest pass.