[sushi] media-bin: fix a compile warning

[Cosimo Cecchi <cosimoc src gnome org>]

commit 6fb5acefb21fa773533ed4b74c4709d783dc646b
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Mon Jun 17 14:59:20 2019 -0700

    media-bin: fix a compile warning

 src/libsushi/sushi-media-bin.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/src/libsushi/sushi-media-bin.c b/src/libsushi/sushi-media-bin.c
index 1e5bba9..17c1fe6 100644
--- a/src/libsushi/sushi-media-bin.c
+++ b/src/libsushi/sushi-media-bin.c
@@ -1815,8 +1815,8 @@ sushi_media_bin_handle_streams_selected (SushiMediaBin *self, GstMessage *msg)
 {
   SushiMediaBinPrivate *priv = SMB_PRIVATE (self);
   GstStreamCollection *collection = NULL;
+  GstStream *stream = NULL;
   GstStructure *caps_struct;
-  GstStream *stream;
   GstCaps *caps;
   gint i, n, w, h;
 
@@ -1831,6 +1831,9 @@ sushi_media_bin_handle_streams_selected (SushiMediaBin *self, GstMessage *msg)
         break;
     }
 
+  if (!stream)
+    return;
+
   caps = gst_stream_get_caps (stream);
   caps_struct = gst_caps_get_structure (caps, 0);