Crash with "Show Detail" Segue

gistfile1.txt

(lldb) bt
* thread #1: tid = 0x6b9a, 0x00000001974c00a8 libobjc.A.dylib`objc_exception_throw, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
    frame #0: 0x00000001974c00a8 libobjc.A.dylib`objc_exception_throw
    frame #1: 0x0000000186c53290 CoreFoundation`-[__NSArrayM insertObject:atIndex:] + 844
    frame #2: 0x000000018b5b7ad0 UIKit`-[UINavigationBar pushNavigationItem:] + 268
    frame #3: 0x000000018b5b78bc UIKit`-[UINavigationBar _pushNavigationItem:transition:] + 392
    frame #4: 0x000000018b7fa334 UIKit`-[UINavigationBar _addItem:withEffectiveDelegate:transition:] + 152
    frame #5: 0x000000018b839bfc UIKit`-[UIViewController _appendNavigationItemsToNavigationController:transition:] + 456
    frame #6: 0x000000018b5b7340 UIKit`__71-[UINavigationController pushViewController:transition:forceImmediate:]_block_invoke + 292
    frame #7: 0x000000018b5d114c UIKit`-[UINavigationController _startDeferredTransitionIfNeeded:] + 980
    frame #8: 0x000000018b5d0d18 UIKit`-[UINavigationController __viewWillLayoutSubviews] + 56
    frame #9: 0x000000018b5d0c98 UIKit`-[UILayoutContainerView layoutSubviews] + 200
    frame #10: 0x000000018b519648 UIKit`-[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 572
    frame #11: 0x000000018ae71994 QuartzCore`-[CALayer layoutSublayers] + 168
    frame #12: 0x000000018ae6c564 QuartzCore`CA::Layer::layout_if_needed(CA::Transaction*) + 320
    frame #13: 0x000000018ae6c408 QuartzCore`CA::Layer::layout_and_display_if_needed(CA::Transaction*) + 32
    frame #14: 0x000000018ae6bc08 QuartzCore`CA::Context::commit_transaction(CA::Transaction*) + 276
    frame #15: 0x000000018ae6b98c QuartzCore`CA::Transaction::commit() + 436
    frame #16: 0x000000018ae653bc QuartzCore`CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) + 80
    frame #17: 0x0000000186d22a50 CoreFoundation`__CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 32
    frame #18: 0x0000000186d1f9dc CoreFoundation`__CFRunLoopDoObservers + 360
    frame #19: 0x0000000186d1fdbc CoreFoundation`__CFRunLoopRun + 836
    frame #20: 0x0000000186c4d0a4 CoreFoundation`CFRunLoopRunSpecific + 396
    frame #21: 0x000000018fdef5a4 GraphicsServices`GSEventRunModal + 168
    frame #22: 0x000000018b5823c0 UIKit`UIApplicationMain + 1488
  * frame #23: 0x0000000100078010 iVocabulary3`main(argc=5, argv=0x000000016fd8f930) + 124 at main.m:116
    frame #24: 0x0000000197b2ea08 libdyld.dylib`start + 4