constrain port in config, catch value error

freqtrade/constants.py

@@ -497,7 +497,12 @@ CONF_SCHEMA = {
                         'properties': {
                             'name': {'type': 'string'},
                             'host': {'type': 'string'},
-                            'port': {'type': 'integer', 'default': 8080},
+                            'port': {
+                                'type': 'integer',
+                                'default': 8080,
+                                'minimum': 0,
+                                'maximum': 65535
+                            },
                             'ws_token': {'type': 'string'},
                         },
                         'required': ['name', 'host', 'ws_token']

freqtrade/rpc/external_message_consumer.py

@@ -205,6 +205,10 @@ class ExternalMessageConsumer:
                     # Now receive data, if none is within the time limit, ping
                     await self._receive_messages(channel, producer, lock)
 
+            except (websockets.exceptions.InvalidURI, ValueError) as e:
+                logger.error(f"{ws_url} is an invalid WebSocket URL - {e}")
+                break
+
             except (
                 socket.gaierror,
                 ConnectionRefusedError,