avfilter: Properly check for failed format query

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

libavfilter/avfiltergraph.c

@@ -559,7 +559,9 @@ static int query_formats(AVFilterGraph *graph, AVClass *log_ctx)
                 if ((ret = avfilter_insert_filter(link, convert, 0, 0)) < 0)
                     return ret;
 
-                filter_query_formats(convert);
+                if ((ret = filter_query_formats(convert)) < 0)
+                    return ret;
+
                 inlink  = convert->inputs[0];
                 outlink = convert->outputs[0];
                 av_assert0( inlink-> in_formats->refcount > 0);