nghttp2_session_resume_data: Return error if no deferred data exist

lib/includes/nghttp2/nghttp2.h

@@ -1848,7 +1848,8 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session,
  * negative error codes:
  *
  * :enum:`NGHTTP2_ERR_INVALID_ARGUMENT`
- *     The stream does not exist or no deferred data exist.
+ *     The stream does not exist; or no deferred data exist; or data
+ *     was deferred by flow control.
  * :enum:`NGHTTP2_ERR_NOMEM`
  *     Out of memory.
  */

lib/nghttp2_session.c

@@ -5468,14 +5468,11 @@ int nghttp2_session_resume_data(nghttp2_session *session, int32_t stream_id)
   nghttp2_stream *stream;
   stream = nghttp2_session_get_stream(session, stream_id);
   if(stream == NULL ||
-     nghttp2_stream_check_deferred_by_flow_control(stream)) {
+     nghttp2_stream_check_deferred_by_flow_control(stream) ||
+     !nghttp2_stream_check_deferred_data(stream)) {
     return NGHTTP2_ERR_INVALID_ARGUMENT;
   }
 
-  if(!nghttp2_stream_check_deferred_data(stream)) {
-    return 0;
-  }
-
   rv = nghttp2_stream_resume_deferred_data(stream, &session->ob_pq);
 
   if(nghttp2_is_fatal(rv)) {