[retro-gtk/to-c] Quick fix

[Adrien Plazas <aplazas src gnome org>]

commit d554f2dd12d3927e6ceb0c600de6931af3a92859
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Fri Jul 7 09:49:16 2017 +0200

    Quick fix

 retro-gtk/retro-core.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/retro-gtk/retro-core.c b/retro-gtk/retro-core.c
index 9427763..d13beae 100644
--- a/retro-gtk/retro-core.c
+++ b/retro-gtk/retro-core.c
@@ -309,6 +309,9 @@ retro_core_set_current_media (RetroCore  *self,
 
   disk_control = retro_core_get_disk_control_interface (self);
 
+  if (disk_control == NULL)
+    return;
+
   retro_disk_control_set_eject_state (disk_control, TRUE, &tmp_error);
   if (tmp_error != NULL) {
     g_propagate_error (error, tmp_error);