add docstring, fix error in brokers and lock module

rasa/core/brokers/kafka.py

@@ -209,10 +209,12 @@ def _publish(self, event: Dict[Text, Any]) -> None:
             f" key={partition_key!s}, headers={headers})"
         )
 
-        self.producer.send(self.topic, value=event, key=partition_key, headers=headers)
+        if self.producer is not None:
+            self.producer.send(self.topic, value=event, key=partition_key, headers=headers)
 
     def _close(self) -> None:
-        self.producer.close()
+        if self.producer is not None:
+            self.producer.close()
 
     @rasa.shared.utils.common.lazy_property
     def rasa_environment(self) -> Optional[Text]:

rasa/core/brokers/pika.py

@@ -244,6 +244,9 @@ async def close(self) -> None:
 
     def is_ready(self) -> bool:
         """Return `True` if a connection was established."""
+        if self._connection is None:
+            return False
+
         return not self._connection.is_closed
 
     def publish(
@@ -262,6 +265,9 @@ def publish(
     async def _publish(
         self, event: Dict[Text, Any], headers: Optional[Dict[Text, Text]] = None
     ) -> None:
+        if self._exchange is None:
+            return
+
         try:
             await self._exchange.publish(self._message(event, headers), "")
 

rasa/core/channels/rest.py

@@ -86,6 +86,7 @@ async def stream(resp: Any) -> None:
     def blueprint(
         self, on_new_message: Callable[[UserMessage], Awaitable[None]]
     ) -> Blueprint:
+        """Groups the collection of endpoints used by rest channel."""
         module_type = inspect.getmodule(self)
         if module_type is not None:
             module_name = module_type.__name__

rasa/core/lock.py

@@ -54,7 +54,7 @@ def __init__(
     def from_dict(cls, data: Dict[Text, Any]) -> "TicketLock":
         """Create `TicketLock` from dictionary."""
 
-        tickets = [Ticket.from_dict(json.loads(d)) for d in data.get("tickets")]
+        tickets = [Ticket.from_dict(json.loads(d)) for d in data.get("tickets", [])]
         return cls(data.get("conversation_id"), deque(tickets))
 
     def dumps(self) -> Text: