When an app external to WizLib changes the state of a bulb, the cached bulb state in WizLib is incorrect.

[PonchoPowers]

One of the bugs I was trying to figure out was why the WizLib library reports an incorrect colour state sometimes, then I realised that if the colour of a bulb is changed by some other software, the WizLib library doesn't know about this and returns what it has cached about the bulb.

This effectively makes the cache return wrong information.

I'm not convinced that you need to cache the bulb state and I'm of the opinion that the caching should be removed in entirety, therefore simplifying the code and removing the need for locks. The bulb itself will then be the single source of truth.