crashlytics – iOS Firebase EXC_BAD_ACCESS KERN_INVALID_ADDRESS

Found multiple crashes in Firebase Crashlytics with following info:
Crashed: com.apple.main-thread
EXC_BAD_ACCESS KERN_INVALID_ADDRESS 0x000000000000002b

          Crashed: com.apple.main-thread
0  KSCrash                        0xbff8 ksmemory_notifyUnhandledFatalSignal + 12
1  KSCrash                        0xcd6c handleSignal + 100
2  libsystem_platform.dylib       0x2a68 _sigtramp + 56
3  libsystem_kernel.dylib         0x439c mach_msg2_internal + 76
4  libsystem_kernel.dylib         0x42b8 mach_msg_overwrite + 428
5  libsystem_kernel.dylib         0x4100 mach_msg + 24
6  CoreFoundation                 0x117a0 __CFRunLoopServiceMachPort + 160
7  CoreFoundation                 0x10090 __CFRunLoopRun + 1208
8  CoreFoundation                 0x11adc CFRunLoopRunSpecific + 572
9  GraphicsServices               0x1454 GSEventRunModal + 168
10 UIKitCore                      0x135274 -[UIApplication _run] + 816
11 UIKitCore                      0x100a28 UIApplicationMain + 336
12 UIKitCore                      0x1e2168 __51-[UIStatusBar_Base _setHidden:animationParameters:]_block_invoke_4 + 180
13 FourPaws                       0xe7999c main + 4387379612 (AppDelegate.swift:4387379612)
14 ???                            0x1c51c9f08 (Missing)

All that I could see from this trace that some variable or object is trying to access an object that’s already been deallocated.

The most confusing points for me are:

1. I couldn’t find any trace of this crash in Organizer.
2. There’s no detail about what’s happening on line 14.
3. At Logs & Breadcrumbs section of Crashlytics I detect various last active VC instead of single one

So the questions is:
Could Firebase Crashlytics be processing the same crash twice, or did a secondary crash happen during the original one, leading to this uninformative stack trace?