Fix JSONDecodeError

Fix #814

gns3server/controller/__init__.py

@@ -127,7 +127,7 @@ class Controller:
                 self.save()
             with open(self._config_file) as f:
                 data = json.load(f)
-        except (OSError, json.JSONDecodeError) as e:
+        except (OSError, json.decoder.JSONDecodeError) as e:
             log.critical("Cannot load %s: %s", self._config_file, str(e))
             return
 

gns3server/controller/topology.py

@@ -112,7 +112,7 @@ def load_topology(path):
     try:
         with open(path, encoding="utf-8") as f:
             topo = json.load(f)
-    except (OSError, UnicodeDecodeError, json.JSONDecodeError) as e:
+    except (OSError, UnicodeDecodeError, json.decoder.JSONDecodeError) as e:
         raise aiohttp.web.HTTPConflict(text="Could not load topology {}: {}".format(path, str(e)))
     if "revision" not in topo or topo["revision"] < 5:
         # If it's an old GNS3 file we need to convert it