Use let keyword for cmpTrigger consistently, so that this reference to the component before deserialization can't be reused inside the Trigger component after deserialization which would cause an OOS on rejoin / savegame loading as experienced prior rP18909.

Differential Revision: https://code.wildfiregames.com/D195
Refs #4310, rP18909, rP18912
Reviewed By: Sandarac