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

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