<__NSArrayM: 0x1708526f0> was mutated while being enumerated.'

[nenhall]

Trapped uncaught exception 'NSGenericException', reason:
'*** Collection <__NSArrayM: 0x1708526f0> was mutated while being enumerated.'
(
0x00000001896721d8 + 148
0x00000001880ac55c objc_exception_throw + 56
0x0000000189671c08 + 0
0x000000010029c98c -[FlyImageRetrieveOperation
0x000000010029cb48 -[FlyImageRetrieveOperation main]
)