[retro-gtk] glsl-dislay: Check shader program exists before using it

[Adrien Plazas <aplazas src gnome org>]

commit ce07f0b629cc0003fccf2a53b3761a8bd84a9754
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Thu Apr 12 01:36:23 2018 +0200

    glsl-dislay: Check shader program exists before using it
    
    This fixes a runtime critical.

 retro-gtk/retro-gl-display.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/retro-gtk/retro-gl-display.c b/retro-gtk/retro-gl-display.c
index da353b3..860e13e 100644
--- a/retro-gtk/retro-gl-display.c
+++ b/retro-gtk/retro-gl-display.c
@@ -285,7 +285,8 @@ retro_gl_display_realize (RetroGLDisplay *self)
     RETRO_VIDEO_FILTER_SMOOTH :
     self->filter;
 
-  retro_glsl_filter_use_program (self->glsl_filter[filter]);
+  if (self->glsl_filter[filter] != NULL)
+    retro_glsl_filter_use_program (self->glsl_filter[filter]);
 }
 
 static void