Fix MQTT connection argument validation (#513)

* Fix MQTT connection argument validation

assert "some string" will never raise an exception

* update error type

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Co-authored-by: Pascal Brogle <[email protected]>

Author: xiazhvera

awsiot/__init__.py

@@ -39,7 +39,7 @@ def __init__(self, mqtt_connection: mqtt.Connection or mqtt5.Client):
             self._mqtt_connection = mqtt_connection.new_connection()
             self._mqtt5_client = mqtt_connection
         else:
-            assert("The service client could only take mqtt.Connection and mqtt5.Client as argument")
+            raise TypeError("The service client could only take mqtt.Connection and mqtt5.Client as argument")
 
     @property
     def mqtt_connection(self) -> mqtt.Connection: