command_name null check before calling .lower()

fixes #534

`AttributeError: 'NoneType' object has no attribute 'lower'`

scripts/main.py

@@ -358,7 +358,7 @@ while True:
             f"COMMAND = {Fore.CYAN}{command_name}{Style.RESET_ALL}  ARGUMENTS = {Fore.CYAN}{arguments}{Style.RESET_ALL}")
 
     # Execute command
-    if command_name.lower() == "error":
+    if command_name is not None and command_name.lower() == "error":
         result = f"Command {command_name} threw the following error: " + arguments
     elif command_name == "human_feedback":
         result = f"Human feedback: {user_input}"