Crash in URLSessionTask didCompleteWithError

[vladlo]

I am getting crash:
Thread 10 Crashed:: Dispatch queue: NSOperationQueue 0x7fc41b480ab0 :: NSOperation 0x7fc4214442c0 (QOS: LEGACY)
0 com.app 0x000000010ceec954 0x10ce2d000 + 784724
1 com.app 0x000000010cee7b78 0x10ce2d000 + 764792
2 com.app 0x000000010cee807e 0x10ce2d000 + 766078
3 net.justHTTP.Just 0x000000010d063b5d TFFC4Just4HTTP7requestFTOS_10HTTPMethod9URLStringSS6paramsGVs10DictionarySSPs9AnyObject__4dataGS2_SSPS3___4jsonGSqPS3___7headersGS2_SSSS_5filesGS2_SSOS_8HTTPFile_4authGSqT8usernameSS8passwordSS__7cookiesGS2_SSSS_9redirectsSb7timeoutGSqSd_8URLQueryGSqSS_11requestBodyGSqCSo6NSData_20asyncProgressHandlerGSqFGSQVS_12HTTPProgress_T__22asyncCompletionHandlerGSqFGSQCS_10HTTPResult_T___S7_U_FS7_T + 77
4 net.justHTTP.Just 0x000000010d05aa18 TPA__TTRXFo_oC4Just10HTTPResult_dT__XFo_iS0__iT_ + 56
5 net.justHTTP.Just 0x000000010d05a622 TTSf4dg_g_g_n___TFC4Just4HTTP10URLSessionfTCSo12NSURLSession4taskCSo16NSURLSessionTask20didCompleteWithErrorGSqCSo7NSError__T + 994
6 net.justHTTP.Just 0x000000010d051d25 TToFC4Just4HTTP10URLSessionfTCSo12NSURLSession4taskCSo16NSURLSessionTask20didCompleteWithErrorGSqCSo7NSError__T + 69
7 com.apple.CFNetwork 0x00007fff91941e9a __51-[NSURLSession delegate_task:didCompleteWithError:]_block_invoke167 + 76
8 com.apple.Foundation 0x00007fff864368d7 NSBLOCKOPERATION_IS_CALLING_OUT_TO_A_BLOCK + 7
9 com.apple.Foundation 0x00007fff86436595 -[NSBlockOperation main] + 100
10 com.apple.Foundation 0x00007fff86434c7a -[__NSOperationInternal _start:] + 654
11 com.apple.Foundation 0x00007fff86430c64 __NSOQSchedule_f + 194
12 libdispatch.dylib 0x00007fff8ef3640b _dispatch_client_callout + 8
13 libdispatch.dylib 0x00007fff8ef3b03b _dispatch_queue_drain + 754
14 libdispatch.dylib 0x00007fff8ef41707 _dispatch_queue_invoke + 549
15 libdispatch.dylib 0x00007fff8ef39d53 _dispatch_root_queue_drain + 538
16 libdispatch.dylib 0x00007fff8ef39b00 _dispatch_worker_thread3 + 91
17 libsystem_pthread.dylib 0x00007fff939074de _pthread_wqthread + 1129
18 libsystem_pthread.dylib 0x00007fff93905341 start_wqthread + 13