Today came across very strange runtime error instantiating CoreML model:

2019-07-24 10:57:07.346799+0300 amt-model-sandbox[16309:2126534] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSURL initFileURLWithPath:]: nil string parameter'
*** First throw call stack:
(
	0   CoreFoundation                      0x0000000106eb26fb __exceptionPreprocess + 331
	1   libobjc.A.dylib                     0x000000010601bac5 objc_exception_throw + 48
	2   CoreFoundation                      0x0000000106eb2555 +[NSException raise:format:] + 197
	3   Foundation                          0x0000000105b22cf3 -[NSURL(NSURL) initFileURLWithPath:] + 127
	4   Foundation                          0x0000000105b2355f +[NSURL(NSURL) fileURLWithPath:] + 45
	5   amt-model-sandbox                   0x0000000104e9a3c9 +[onset_frames urlOfModelInThisBundle] + 169
	6   amt-model-sandbox                   0x0000000104e9a43c -[onset_frames init] + 60
	7   amt-model-sandbox                   0x0000000104ea1133 $sSo12onset_framesCABSgycfcTO + 19
	8   amt-model-sandbox                   0x0000000104e9dc4f $sSo12onset_framesCABSgycfC + 31
	9   amt-model-sandbox                   0x0000000104e9b554 $s17amt_model_sandbox14ViewControllerC11viewDidLoadyyF + 580
	10  amt-model-sandbox                   0x0000000104e9e6b4 $s17amt_model_sandbox14ViewControllerC11viewDidLoadyyFTo + 36
	11  UIKitCore                           0x00000001119bc43b -[UIViewController loadViewIfRequired] + 1183
	12  UIKitCore                           0x00000001119bc868 -[UIViewController view] + 27
	13  UIKitCore                           0x0000000111ff4c33 -[UIWindow addRootViewControllerViewIfPossible] + 122
	14  UIKitCore                           0x0000000111ff5327 -[UIWindow _setHidden:forced:] + 289
	15  UIKitCore                           0x0000000112007f86 -[UIWindow makeKeyAndVisible] + 42
	16  UIKitCore                           0x0000000111fb7f1c -[UIApplication _callInitializationDelegatesForMainScene:transitionContext:] + 4555
	17  UIKitCore                           0x0000000111fbd0c6 -[UIApplication _runWithMainScene:transitionContext:completion:] + 1617
	18  UIKitCore                           0x00000001118026d6 __111-[__UICanvasLifecycleMonitor_Compatability _scheduleFirstCommitForScene:transition:firstActivation:completion:]_block_invoke + 904
	19  UIKitCore                           0x000000011180afce +[_UICanvas _enqueuePostSettingUpdateTransactionBlock:] + 153
	20  UIKitCore                           0x00000001118022ec -[__UICanvasLifecycleMonitor_Compatability _scheduleFirstCommitForScene:transition:firstActivation:completion:] + 236
	21  UIKitCore                           0x0000000111802c48 -[__UICanvasLifecycleMonitor_Compatability activateEventsOnly:withContext:completion:] + 1091
	22  UIKitCore                           0x0000000111800fba __82-[_UIApplicationCanvas _transitionLifecycleStateWithTransitionContext:completion:]_block_invoke + 782
	23  UIKitCore                           0x0000000111800c71 -[_UIApplicationCanvas _transitionLifecycleStateWithTransitionContext:completion:] + 433
	24  UIKitCore                           0x00000001118059b6 __125-[_UICanvasLifecycleSettingsDiffAction performActionsForCanvas:withUpdatedScene:settingsDiff:fromSettings:transitionContext:]_block_invoke + 576
	25  UIKitCore                           0x0000000111806610 _performActionsWithDelayForTransitionContext + 100
	26  UIKitCore                           0x000000011180571d -[_UICanvasLifecycleSettingsDiffAction performActionsForCanvas:withUpdatedScene:settingsDiff:fromSettings:transitionContext:] + 223
	27  UIKitCore                           0x000000011180a6d0 -[_UICanvas scene:didUpdateWithDiff:transitionContext:completion:] + 392
	28  UIKitCore                           0x0000000111fbb9a8 -[UIApplication workspace:didCreateScene:withTransitionContext:completion:] + 514
	29  UIKitCore                           0x0000000111b72dfa -[UIApplicationSceneClientAgent scene:didInitializeWithEvent:completion:] + 361
	30  FrontBoardServices                  0x00000001109da125 -[FBSSceneImpl _didCreateWithTransitionContext:completion:] + 448
	31  FrontBoardServices                  0x00000001109e3ed6 __56-[FBSWorkspace client:handleCreateScene:withCompletion:]_block_invoke_2 + 283
	32  FrontBoardServices                  0x00000001109e3700 __40-[FBSWorkspace _performDelegateCallOut:]_block_invoke + 53
	33  libdispatch.dylib                   0x0000000107f78db5 _dispatch_client_callout + 8
	34  libdispatch.dylib                   0x0000000107f7c2ba _dispatch_block_invoke_direct + 300
	35  FrontBoardServices                  0x0000000110a15146 __FBSSERIALQUEUE_IS_CALLING_OUT_TO_A_BLOCK__ + 30
	36  FrontBoardServices                  0x0000000110a14dfe -[FBSSerialQueue _performNext] + 451
	37  FrontBoardServices                  0x0000000110a15393 -[FBSSerialQueue _performNextFromRunLoopSource] + 42
	38  CoreFoundation                      0x0000000106e19be1 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
	39  CoreFoundation                      0x0000000106e19463 __CFRunLoopDoSources0 + 243
	40  CoreFoundation                      0x0000000106e13b1f __CFRunLoopRun + 1231
	41  CoreFoundation                      0x0000000106e13302 CFRunLoopRunSpecific + 626
	42  GraphicsServices                    0x000000010b7822fe GSEventRunModal + 65
	43  UIKitCore                           0x0000000111fbeba2 UIApplicationMain + 140
	44  amt-model-sandbox                   0x0000000104ea1e9b main + 75
	45  libdyld.dylib                       0x0000000107fed541 start + 1
	46  ???                                 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

Solution was unexpected. Changing CoreML Model Class Generation Language parameter from Automatic to Swift, firstly, solved this runtime bug. Second, Xcode started generate Swift but not Objective-C class for CoreML model. Don’t know why in case of Automatic parameter it generated Objective-C code.