"Assertion," in this context, is a way to test for a condition or set a condition to test against. It is a programming tool.
What you are seeing here is a bug-related crash because the assertion was made, the assertion failed (in module "gt96k_timer.c," line 771), but the exception was not handled for when the assertion failed.
You might want to try another version of IOS (update or downrev). If that's not possible, try setting up the actions in a different order.
Good Luck
Scott
