[Bug] Possible invalid transition in Timer FSM

[Sushisource]

What are you really trying to do?

Describe the bug

It appears that it's possible for a Timer to fire at the same time that the SDK is replying requesting to cancel it, resulting in:

TimerMachine in state CancelTimerCommandSent says the transition is invalid during event EventInfo { event_id: 22, event_type: TimerFired }\")"

Minimal Reproduction

Need to make one. Seemingly getting a timer to fire and having that event be in the MS buffer while also replying with a request to cancel might trigger it.

WF history of a user-reported incident below. df709234-7d60-47f4-b1fa-717c3040e62a_events.json