[gjs/gbsneto/fundamental-fixes] fundamental: Check if gtype is valid before using it

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 0ce728079290c0a763cd1bf6a32e7ea5ba5862ba
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Tue Oct 9 19:52:39 2018 -0300

    fundamental: Check if gtype is valid before using it
    
    Not a big deal, but found this bug while investigating some
    problems that arose from https://gitlab.gnome.org/GNOME/mutter/merge_requests/260.
    
    We should check if the GType is valid before using it, not
    after.

 gi/fundamental.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/gi/fundamental.cpp b/gi/fundamental.cpp
index a5e1ce95..04332f78 100644
--- a/gi/fundamental.cpp
+++ b/gi/fundamental.cpp
@@ -629,10 +629,10 @@ gjs_lookup_fundamental_prototype_from_gtype(JSContext *context,
     /* A given gtype might not have any definition in the introspection
      * data. If that's the case, try to look for a definition of any of the
      * parent type. */
-    while ((info = (GIObjectInfo *)
+    while (gtype != G_TYPE_INVALID &&
+           (info = (GIObjectInfo *)
             g_irepository_find_by_gtype(g_irepository_get_default(),
-                                        gtype)) == NULL &&
-           gtype != G_TYPE_INVALID)
+                                        gtype)) == NULL)
         gtype = g_type_parent(gtype);
 
     proto = gjs_lookup_fundamental_prototype(context, info, gtype);