lavc/videotoolboxdec: warn on nonzero status in the callback

Signed-off-by: rcombs <rcombs@rcombs.me>

libavcodec/videotoolbox.c

@@ -691,7 +691,7 @@ static void videotoolbox_decoder_callback(void *opaque,
     }
 
     if (!image_buffer) {
-        av_log(avctx, AV_LOG_DEBUG, "vt decoder cb: output image buffer is null\n");
+        av_log(avctx, status ? AV_LOG_WARNING : AV_LOG_DEBUG, "vt decoder cb: output image buffer is null: %i\n", status);
         return;
     }