[gjs] object: Check for error on gjs_value_to_g_value()

[Philip Chimento <pchimento src gnome org>]

commit b136107eef97db27b12fafe74e86fe29f8ebd772
Author: Philip Chimento <philip chimento gmail com>
Date:   Mon Sep 26 23:10:45 2016 -0700

    object: Check for error on gjs_value_to_g_value()
    
    Without this error check, it is possible for an exception to be left
    pending, and mozjs will assert about that if compiled with debug flags.
    
    Adding the error check exposed an additional bug in
    testExceptionInPropertySetterWithBinding(); without the G_PARAM_CONSTRUCT
    flag the getter would return undefined because the property had never
    been set.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=573335

 gi/object.cpp                        |    5 ++---
 installed-tests/js/testExceptions.js |    3 ++-
 2 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/gi/object.cpp b/gi/object.cpp
index cfca5d3..ba8d663 100644
--- a/gi/object.cpp
+++ b/gi/object.cpp
@@ -2402,10 +2402,9 @@ gjs_object_get_gproperty (GObject    *object,
     js_obj = peek_js_obj(object);
 
     underscore_name = hyphen_to_underscore((gchar *)pspec->name);
-    if (!JS_GetProperty(context, js_obj, underscore_name, &jsvalue))
+    if (!JS_GetProperty(context, js_obj, underscore_name, &jsvalue) ||
+        !gjs_value_to_g_value(context, jsvalue, value))
         gjs_log_exception(context);
-    else
-        gjs_value_to_g_value(context, jsvalue, value);
     g_free (underscore_name);
 }
 
diff --git a/installed-tests/js/testExceptions.js b/installed-tests/js/testExceptions.js
index c69a0c9..2a12fff 100644
--- a/installed-tests/js/testExceptions.js
+++ b/installed-tests/js/testExceptions.js
@@ -23,7 +23,8 @@ const Bar = new Lang.Class({
     Name: 'Bar',
     Extends: GObject.Object,
     Properties: {
-        'prop': GObject.ParamSpec.string('prop', '', '', GObject.ParamFlags.READWRITE, '')
+        'prop': GObject.ParamSpec.string('prop', '', '',
+            GObject.ParamFlags.READWRITE | GObject.ParamFlags.CONSTRUCT, ''),
     }
 });