QUIC: revised ngx_quic_handle_datagram() error codes. The NGX_DECLINED is replaced with NGX_DONE to match closer to return code of ngx_quic_handle_packet() and ngx_quic_close_connection() rc argument. The ngx_quic_close_connection() rc code is used only when quic connection exists, thus anything goes if qc == NULL. The ngx_quic_handle_datagram() does not return NG_OK in cases when quic connection is not yet created.

--- a/src/event/quic/ngx_event_quic_output.c
+++ b/src/event/quic/ngx_event_quic_output.c
@@ -979,7 +979,7 @@ ngx_quic_send_early_cc(ngx_connection_t 
         return NGX_ERROR;
     }
 
-    return NGX_OK;
+    return NGX_DONE;
 }