src/third_party/mozjs-45/js/src/jit-test/tests/debug/onExceptionUnwind-05.js

// onExceptionUnwind returning undefined does not affect the thrown exception.

var g = newGlobal();
g.parent = this;
g.eval("new Debugger(parent).onExceptionUnwind = function () {};");

var obj = new Error("oops");
try {
    throw obj;
} catch (exc) {
    assertEq(exc, obj);
}