glcolorconvert: Don't copy overlay composition meta over to NULL outbufs

gst-libs/gst/gl/gstglcolorconvert.c

diff --git a/gst-libs/gst/gl/gstglcolorconvert.c b/gst-libs/gst/gl/gstglcolorconvert.c
index 43d2caf..60d9653 100644
--- a/gst-libs/gst/gl/gstglcolorconvert.c
+++ b/gst-libs/gst/gl/gstglcolorconvert.c
@@ -2324,7 +2324,6 @@
   struct ConvertInfo *c_info = &convert->priv->convert_info;
   gboolean res = TRUE;
   gint views, v;
-  GstVideoOverlayCompositionMeta *composition_meta;
   GstGLSyncMeta *sync_meta;
   GstFlowReturn ret;
 
@@ -2440,19 +2439,20 @@
   }
 
   if (convert->outbuf) {
+    GstVideoOverlayCompositionMeta *composition_meta;
     GstGLSyncMeta *sync_meta =
         gst_buffer_add_gl_sync_meta (convert->context, convert->outbuf);
 
     if (sync_meta)
       gst_gl_sync_meta_set_sync_point (sync_meta, convert->context);
-  }
 
-  composition_meta =
-      gst_buffer_get_video_overlay_composition_meta (convert->inbuf);
-  if (composition_meta) {
-    GST_DEBUG ("found video overlay composition meta, applying on output.");
-    gst_buffer_add_video_overlay_composition_meta
-        (convert->outbuf, composition_meta->overlay);
+    composition_meta =
+        gst_buffer_get_video_overlay_composition_meta (convert->inbuf);
+    if (composition_meta) {
+      GST_DEBUG ("found video overlay composition meta, applying on output.");
+      gst_buffer_add_video_overlay_composition_meta
+          (convert->outbuf, composition_meta->overlay);
+    }
   }
 
   convert->priv->result = res;