Uncaught TypeError and Unreliable events (Construct 3)

I have a turn-based game made in Construct 3 + Photon.

Often when receiving events, this message appears on the console. But most of the time the game seems to work fine. What does that mean?

Same about:

[Operation 252 error: CAS update failed on server (-2)

actions.js:5 ERROR: CAS update failed on server - CODE: -2]

Occasionally one of the players starts -maybe- not receiving some events, and has problems continuing the game because of it. Could this error be related to the problem? Or could it be some unreliable event? How do I find out if the event in the Construct is unreleable or releable?

Photon Addon version