[gjs: 14/15] repo: Fix error handling in lookup functions

[Cosimo Cecchi <cosimoc src gnome org>]

commit 6635a418de4a00a41a5251cdd8db7e22080ed61d
Author: Philip Chimento <philip chimento gmail com>
Date:   Sat Dec 22 15:38:08 2018 -0700

    repo: Fix error handling in lookup functions
    
    In gjs_lookup_generic_constructor() and gjs_lookup_generic_prototype(),
    the case where the constructor or prototype existed, but was not an
    object, was not handled properly. An exception needed to be thrown.

 gi/repo.cpp | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)
---
diff --git a/gi/repo.cpp b/gi/repo.cpp
index 7b0c9fd4..9c2e848c 100644
--- a/gi/repo.cpp
+++ b/gi/repo.cpp
@@ -747,8 +747,12 @@ gjs_lookup_generic_constructor(JSContext  *context,
     if (!JS_GetProperty(context, in_object, constructor_name, &value))
         return NULL;
 
-    if (G_UNLIKELY (!value.isObject()))
+    if (G_UNLIKELY(!value.isObject())) {
+        gjs_throw(context,
+                  "Constructor of %s.%s was the wrong type, expected an object",
+                  g_base_info_get_namespace(info), constructor_name);
         return NULL;
+    }
 
     return &value.toObject();
 }
@@ -767,8 +771,12 @@ gjs_lookup_generic_prototype(JSContext  *context,
     if (!JS_GetPropertyById(context, constructor, atoms.prototype(), &value))
         return NULL;
 
-    if (G_UNLIKELY (!value.isObjectOrNull()))
+    if (G_UNLIKELY(!value.isObject())) {
+        gjs_throw(context,
+                  "Prototype of %s.%s was the wrong type, expected an object",
+                  g_base_info_get_namespace(info), g_base_info_get_name(info));
         return NULL;
+    }
 
-    return value.toObjectOrNull();
+    return &value.toObject();
 }