Better error message if using new device manager without the new environment variable

[olliesilvester]

If BlueAPI is running and using a dodal module which defines its devices using the new device factory, eg like

@devices.factory()
def smargon() -> Smargon:
    return Smargon(f"{PREFIX.beamline_prefix}-MO-SGON-01:")

and if the blueapi's values.yaml is missing the new environment variable required, eg

        - kind: deviceManager
          module: dodal.beamlines.i04

then posting a plan will give a BlueAPI validation error which isn't very obvious. The message body on the validation error response looks like: Value error, Device smargon is not of type dodal.devices.smargon.Smargon (etc for all devices in the plan you were trying to run). I didn't really have any idea where to look from that error message.

It would be really helpful if the error message pointed out that the deviceManager configuration was missing

[tpoliaw]

This is partly covered by #1194 (and relates to #1193)

It's difficult to tell in blueapi that a module should use deviceManager instead of dodal but we should definitely improve the error message.

• We should deprecate the dodal version and warn if anyone is using it. We are aiming to remove the dodal dependency soon so this will help with that.
• We should merge fix: Give better error message on non-existent device #1194 so that the error differentiates between something being the wrong type and the device not existing
• We should log a warning if no devices have been configured with a message along the lines of "check modules are included and have the correct 'kind' field".

Would that help debug situations like this?

[olliesilvester]

Yes, that all sounds good thanks