Force reconnection when a null message is received

[mattiekat]

I am not fully certain on what grounds a null message occurs, however, I ran across this issue when switching to this library thanks to a test case someone now long gone wrote.

Specifically, it checked to make sure that the system would handle a queue being deleted and recreated. This results in a null message which our old system used as a trigger for reconnecting.

As far as I can tell, there is no valid way to reconnect so I ended up writing await this.connectionWrapper._currentConnection.close() to force a reconnection. This feels fundamentally wrong, but it did fix the test case.