Fix Pylance issues in client.py

[RJCD-Diamond]

There are a load of problems that are raised by pylance in the client.py. These should be fixed

[DiamondJoseph]

Can you give examples?

I just loaded the devcontainer and client.py is completely fine, as was it when I made a venv locally and set it as the active python interpreter.

Were you using the devcontainer?
If not, was blueapi and its dependencies installed into your active venv?
Do you have any custom pylance configuration?