[gnome-shell] st: Don't assert when corner texture creation fails

[Florian Müllner <fmuellner src gnome org>]

commit 8416ba25de3797c1fdfd49b2a598f3e380713129
Author: Florian Müllner <fmuellner gnome org>
Date:   Fri Apr 15 19:05:04 2016 +0200

    st: Don't assert when corner texture creation fails

 src/st/st-theme-node-drawing.c |   11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)
---
diff --git a/src/st/st-theme-node-drawing.c b/src/st/st-theme-node-drawing.c
index 057b716..85feb20 100644
--- a/src/st/st-theme-node-drawing.c
+++ b/src/st/st-theme-node-drawing.c
@@ -182,7 +182,6 @@ create_corner_material (StCornerSpec *corner)
     }
 
   g_free (data);
-  g_assert (texture != COGL_INVALID_HANDLE);
 
   return texture;
 }
@@ -355,7 +354,7 @@ st_theme_node_lookup_corner (StThemeNode    *node,
                              float           height,
                              StCorner        corner_id)
 {
-  CoglHandle texture, material;
+  CoglHandle texture, material = COGL_INVALID_HANDLE;
   char *key;
   StTextureCache *cache;
   StCornerSpec corner;
@@ -404,8 +403,12 @@ st_theme_node_lookup_corner (StThemeNode    *node,
 
   key = corner_to_string (&corner);
   texture = st_texture_cache_load (cache, key, ST_TEXTURE_CACHE_POLICY_NONE, load_corner, &corner, NULL);
-  material = _st_create_texture_pipeline (texture);
-  cogl_handle_unref (texture);
+
+  if (texture)
+    {
+      material = _st_create_texture_pipeline (texture);
+      cogl_handle_unref (texture);
+    }
 
   g_free (key);