Improve error message when a project cannot be parsed.

gns3server/controller/topology.py

@@ -188,7 +188,7 @@ def load_topology(path):
     try:
         _check_topology_schema(topo)
     except aiohttp.web.HTTPConflict as e:
-        log.error("Can't load the topology %s", path)
+        log.error("Can't load the topology %s, please check using the debug mode...", path)
         raise e
 
     if changed: