[gjs/gnome-3-34] object: Handle error from gjs_callback_trampoline_new()

[Philip Chimento <pchimento src gnome org>]

commit cf8ca947647f395438eaddfb85458bc186ae1ab1
Author: Philip Chimento <philip chimento gmail com>
Date:   Sun Oct 27 17:47:19 2019 -0700

    object: Handle error from gjs_callback_trampoline_new()
    
    This fixes the crash mentioned in #72. The functionality of overriding
    vfuncs with callbacks as parameters is still not supported, but now it
    will throw an exception instead of crashing.
    
    See: #72

 gi/object.cpp                          | 2 ++
 installed-tests/js/testGObjectClass.js | 8 ++++++++
 2 files changed, 10 insertions(+)
---
diff --git a/gi/object.cpp b/gi/object.cpp
index 6012e5b2..048233db 100644
--- a/gi/object.cpp
+++ b/gi/object.cpp
@@ -2316,6 +2316,8 @@ bool ObjectPrototype::hook_up_vfunc_impl(JSContext* cx,
         JS::RootedFunction func(cx, JS_GetObjectFunction(function));
         trampoline = gjs_callback_trampoline_new(
             cx, func, vfunc, GI_SCOPE_TYPE_NOTIFIED, prototype, true);
+        if (!trampoline)
+            return false;
 
         *((ffi_closure **)method_ptr) = trampoline->closure;
     }
diff --git a/installed-tests/js/testGObjectClass.js b/installed-tests/js/testGObjectClass.js
index 77c6f3ab..a9d209e8 100644
--- a/installed-tests/js/testGObjectClass.js
+++ b/installed-tests/js/testGObjectClass.js
@@ -452,6 +452,14 @@ describe('GObject virtual function', function () {
 
         expect(() => GObject.registerClass({GTypeName: 'SimpleTestClass3'}, _SimpleTestClass3)).toThrow();
     });
+
+    it('gracefully bails out when overriding an unsupported vfunc type', function () {
+        expect(() => GObject.registerClass({
+            Implements: [Gio.AsyncInitable],
+        }, class Foo extends GObject.Object {
+            vfunc_init_async() {}
+        })).toThrow();
+    });
 });
 
 describe('GObject creation using base classes without registered GType', function () {