[totem/wip/hadess/missing-plugins-check: 2/6] backend: Fix warning if glsinkbin plugin is missing

[Bastien Nocera <hadess src gnome org>]

commit 59ad2f1f98d8161915d15f7b95a7abc2be548aa1
Author: Bastien Nocera <hadess hadess net>
Date:   Tue Mar 29 09:58:21 2022 +0200

    backend: Fix warning if glsinkbin plugin is missing
    
    (totem:400643): GStreamer-CRITICAL **: 09:56:08.831: gst_bus_set_flushing: assertion 'GST_IS_BUS (bus)' 
failed
    
     #0  0x00007ffff7de2df1 in g_logv () at /lib64/libglib-2.0.so.0
     #1  0x00007ffff7de3073 in g_log () at /lib64/libglib-2.0.so.0
     #2  0x00007ffff7f89be6 in bvw_stop_play_pipeline (bvw=bvw@entry=0x777d10) at 
../../../../Projects/jhbuild/totem/src/backend/bacon-video-widget.c:3852
     #3  0x00007ffff7f8ef6f in bacon_video_widget_close (bvw=0x777d10) at 
../../../../Projects/jhbuild/totem/src/backend/bacon-video-widget.c:3902
     #4  0x00007ffff7f7b381 in totem_object_exit (totem=totem@entry=0x44f670) at 
../../../../Projects/jhbuild/totem/src/totem-object.c:1405
    
     #2  0x00007ffff7f89be6 in bvw_stop_play_pipeline (bvw=bvw@entry=0x777d10) at 
../../../../Projects/jhbuild/totem/src/backend/bacon-video-widget.c:3852
     3852     gst_bus_set_flushing (bvw->bus, TRUE);
     (gdb) p bvw->bus
     $1 = 0x0

 src/backend/bacon-video-widget.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/backend/bacon-video-widget.c b/src/backend/bacon-video-widget.c
index 9ff2e9cc8..6435ed951 100644
--- a/src/backend/bacon-video-widget.c
+++ b/src/backend/bacon-video-widget.c
@@ -3849,7 +3849,8 @@ bvw_stop_play_pipeline (BaconVideoWidget * bvw)
   /* and now drop all following messages until we start again. The
    * bus is set to flush=false again in bacon_video_widget_open()
    */
-  gst_bus_set_flushing (bvw->bus, TRUE);
+  if (bvw->bus)
+    gst_bus_set_flushing (bvw->bus, TRUE);
 
   /* Now in READY or lower */
   bvw->target_state = GST_STATE_READY;