Explicit cast

gistfile1.txt

Unhandled Exception:
System.InvalidCastException: Specified cast is not valid.
2017-09-10 17:45:29.092 DragBoard[4826:1336326] Unhandled managed exception:
Specified cast is not valid. (System.InvalidCastException)
(null)
2017-09-10 17:45:29.092 DragBoard[4826:1336326] critical: Stacktrace:

2017-09-10 17:45:29.092 DragBoard[4826:1336326] critical: 
Native stacktrace:

2017-09-10 17:45:29.142 DragBoard[4826:1336326] critical: 	0   DragBoard                           0x00000001077fb7c4 mono_handle_native_crash + 244
2017-09-10 17:45:29.142 DragBoard[4826:1336326] critical: 	1   libsystem_platform.dylib            0x00000001161b1f5a _sigtramp + 26
2017-09-10 17:45:29.142 DragBoard[4826:1336326] critical: 	2   ???                                 0x0000ffff00001fa0 0x0 + 281470681751456
2017-09-10 17:45:29.143 DragBoard[4826:1336326] critical: 	3   libsystem_c.dylib                   0x0000000115d7a107 abort + 127
2017-09-10 17:45:29.143 DragBoard[4826:1336326] critical: 	4   DragBoard                           0x00000001079be04f xamarin_unhandled_exception_handler + 47
2017-09-10 17:45:29.143 DragBoard[4826:1336326] critical: 	5   DragBoard                           0x00000001078655b4 mono_invoke_unhandled_exception_hook + 148
2017-09-10 17:45:29.143 DragBoard[4826:1336326] critical: 	6   DragBoard                           0x00000001077fb2cb mono_handle_exception_internal + 4971
2017-09-10 17:45:29.143 DragBoard[4826:1336326] critical: 	7   DragBoard                           0x00000001077f9f58 mono_handle_exception + 24
2017-09-10 17:45:29.144 DragBoard[4826:1336326] critical: 	8   DragBoard                           0x000000010777c91f mono_amd64_throw_exception + 143
2017-09-10 17:45:29.144 DragBoard[4826:1336326] critical: 	9   ???                                 0x0000000130ef6ae7 0x0 + 5115964135
2017-09-10 17:45:29.144 DragBoard[4826:1336326] critical: 	10  DragBoard                           0x00000001079bdc47 xamarin_process_managed_exception_gchandle + 55
2017-09-10 17:45:29.144 DragBoard[4826:1336326] critical: 	11  DragBoard                           0x00000001079bdc03 xamarin_ftnptr_exception_handler + 19
2017-09-10 17:45:29.144 DragBoard[4826:1336326] critical: 	12  ???                                 0x00000001350ebbf5 0x0 + 5185125365
2017-09-10 17:45:29.144 DragBoard[4826:1336326] critical: 	13  Foundation                          0x0000000108d9ffa2 __63-[NSItemProvider _loadObjectOfClass:options:completionHandler:]_block_invoke.381 + 133
2017-09-10 17:45:29.145 DragBoard[4826:1336326] critical: 	14  libdispatch.dylib                   0x0000000115c32273 _dispatch_call_block_and_release + 12
2017-09-10 17:45:29.145 DragBoard[4826:1336326] critical: 	15  libdispatch.dylib                   0x0000000115c332b5 _dispatch_client_callout + 8
2017-09-10 17:45:29.145 DragBoard[4826:1336326] critical: 	16  libdispatch.dylib                   0x0000000115c3ae3f _dispatch_queue_serial_drain + 654
2017-09-10 17:45:29.145 DragBoard[4826:1336326] critical: 	17  libdispatch.dylib                   0x0000000115c3b690 _dispatch_queue_invoke + 329
2017-09-10 17:45:29.145 DragBoard[4826:1336326] critical: 	18  libdispatch.dylib                   0x0000000115c37d94 _dispatch_queue_override_invoke + 477
2017-09-10 17:45:29.145 DragBoard[4826:1336326] critical: 	19  libdispatch.dylib                   0x0000000115c3da72 _dispatch_root_queue_drain + 568
2017-09-10 17:45:29.145 DragBoard[4826:1336326] critical: 	20  libdispatch.dylib                   0x0000000115c3d7dc _dispatch_worker_thread3 + 119
2017-09-10 17:45:29.146 DragBoard[4826:1336326] critical: 	21  libsystem_pthread.dylib             0x00000001161c31ca _pthread_wqthread + 1387
2017-09-10 17:45:29.146 DragBoard[4826:1336326] critical: 	22  libsystem_pthread.dylib             0x00000001161c2c4d start_wqthread + 13
2017-09-10 17:45:29.146 DragBoard[4826:1336326] critical: 
=================================================================
Got a SIGABRT while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries 
used by your application.
=================================================================