Only print normal messages that actually have text

No support for invites/introductions

briar-cli.py

@@ -65,7 +65,8 @@ def get_message_stdin(token):
 def print_message(message):
     prefix = '>' if message['local'] else '<'
     time = get_timestamp(datetime.fromtimestamp(message['timestamp'] / 1000))
-    print(f"{time} {prefix} {message['text']}")
+    if 'text' in message:
+        print(f"{time} {prefix} {message['text']}")
 
 
 def get_timestamp(date):