MagicalRecord crash

Thread 0 name:  Dispatch queue: com.apple.main-thread
Thread 0 Crashed:
0   libobjc.A.dylib                 0x390105b0 objc_msgSend + 16
1   Foundation                      0x31b60520 -[NSError dealloc] + 56
2   libobjc.A.dylib                 0x39012484 (anonymous namespace)::AutoreleasePoolPage::pop(void*) + 164
3   CoreFoundation                  0x3123043c _CFAutoreleasePoolPop + 12
4   CoreFoundation                  0x312c0f3c __CFRunLoopRun + 1292
5   CoreFoundation                  0x31233eb8 CFRunLoopRunSpecific + 352
6   CoreFoundation                  0x31233d44 CFRunLoopRunInMode + 100
7   GraphicsServices                0x34e0c2e6 GSEventRunModal + 70
8   UIKit                           0x331492fc UIApplicationMain + 1116
9   PAM                             0x0009f402 main (main.m:16)
10  libdyld.dylib                   0x3944cb1c start + 0

Thread 1:
0   libsystem_kernel.dylib          0x39513d98 __workq_kernreturn + 8
1   libsystem_c.dylib               0x39461cf6 _pthread_workq_return + 14
2   libsystem_c.dylib               0x39461a12 _pthread_wqthread + 362
3   libsystem_c.dylib               0x394618a0 start_wqthread + 4

[…]

Thread 8 name:  Dispatch queue: NSManagedObjectContext Queue
Thread 8:
0   libobjc.A.dylib                 0x39012526 objc_retain + 6
1   PAM                             0x000b7268 +[MagicalRecord(ErrorHandling) defaultErrorHandler:] (MagicalRecord+ErrorHandling.m:26)
2   PAM                             0x000b7422 +[MagicalRecord(ErrorHandling) handleErrors:] (MagicalRecord+ErrorHandling.m:68)
3   PAM                             0x000b43d2 -[NSManagedObjectContext(MagicalRecord) MR_contextWillSave:] (NSManagedObjectContext+MagicalRecord.m:231)
4   CoreFoundation                  0x3123e034 _CFXNotificationPost + 1424
5   Foundation                      0x31b54594 -[NSNotificationCenter postNotificationName:object:userInfo:] + 68
6   CoreData                        0x310e6526 -[NSManagedObjectContext save:] + 286
7   PAM                             0x000b46b0 __70-[NSManagedObjectContext(MagicalSaves) MR_saveWithOptions:completion:]_block_invoke3 (NSManagedObjectContext+MagicalSaves.m:64)
8   CoreData                        0x310ea072 developerSubmittedBlockToNSManagedObjectContextPerform_privateasync + 66
9   libdispatch.dylib               0x39430eca _dispatch_queue_drain$VARIANT$mp + 138
10  libdispatch.dylib               0x39430dbc _dispatch_queue_invoke$VARIANT$mp + 36
11  libdispatch.dylib               0x3943191a _dispatch_root_queue_drain + 182
12  libdispatch.dylib               0x39431abc _dispatch_worker_thread2 + 80
13  libsystem_c.dylib               0x39461a0e _pthread_wqthread + 358
14  libsystem_c.dylib               0x394618a0 start_wqthread + 4