Warning: CHC: Empty array "pop" happens here.
Counterexample:
arr = []
a = 0x0
x = 0

Transaction trace:
test.constructor()
State: arr = []
test.f(0x0, 1)
  --> model_checker_targets_pop_empty_chc/input.sol:12:3:
   |
12 | 		arr.pop();
   | 		^^^^^^^^^