[CrashReport] Mac assertion - FSourceCodeNavigationImpl::NavigateToFunctionSource()

LogMetal: Display: Loaded a text shader (will be slower to load)
LogSlate: Took 0.003841 seconds to synchronously load lazily loaded font '../../../Engine/Content/Editor/Slate/Fonts/Roboto-Italic.ttf' (157K)
LogContentBrowser: Native class hierarchy updated for 'BlueprintGraph' in 0.0013 seconds. Added 116 classes and 0 folders.
LogSlate: Took 0.000965 seconds to synchronously load lazily loaded font '../../../Engine/Content/Editor/Slate/Fonts/Roboto-BoldCondensed.ttf' (158K)
Error: appError called: Assertion failed: Count >= 0 [File:Runtime/Core/Public/Containers/UnrealString.h] [Line: 1167] 


=== Critical error: ===
SIGSEGV: invalid attempt to access memory at address 0x3

0x019960db UE4Editor-Core.dylib!FGenericPlatformMisc::RaiseException(unsigned int)   [UnknownFile]) 
0x0332bef9 UE4Editor-ApplicationCore.dylib!FMacErrorOutputDevice::Serialize(wchar_t const*, ELogVerbosity::Type, FName const&)   [UnknownFile]) 
0x01c43f6d UE4Editor-Core.dylib!FOutputDevice::Logf(wchar_t const*, ...)   [UnknownFile]) 
0x01bba5fb UE4Editor-Core.dylib!FDebug::AssertFailed(char const*, char const*, int, wchar_t const*, ...)   [UnknownFile]) 
0x099db28a UE4Editor-UnrealEd.dylib!FSourceCodeNavigationImpl::NavigateToFunctionSource(FString const&, FString const&, bool)   [UnknownFile]) 
0x099dd301 UE4Editor-UnrealEd.dylib!FSourceCodeNavigation::NavigateToFunctionSourceAsync(FString const&, FString const&, bool)::FLocal::NavigateToFunctionSourceTaskWrapper(ENamedThreads::Type, TRefCountPtr<FGraphEvent> const&, TSharedRef<FSourceCodeNavigation::NavigateToFunctionSourceAsync(FString const&, FString const&, bool)::FNavigateFunctionParams, (ESPMode)0>, TSharedPtr<SNotificationItem, (ESPMode)0>)   [UnknownFile]) 
0x09ab1021 UE4Editor-UnrealEd.dylib!TBaseStaticDelegateInstance<TTypeWrapper<void> (ENamedThreads::Type, TRefCountPtr<FGraphEvent> const&), TSharedRef<FSourceCodeNavigation::NavigateToFunctionSourceAsync(FString const&, FString const&, bool)::FNavigateFunctionParams, (ESPMode)0>, TSharedPtr<SNotificationItem, (ESPMode)0> >::Execute(ENamedThreads::Type, TRefCountPtr<FGraphEvent> const&) const   [UnknownFile]) 
0x09ab10f9 UE4Editor-UnrealEd.dylib!TBaseStaticDelegateInstance<void (ENamedThreads::Type, TRefCountPtr<FGraphEvent> const&), TSharedRef<FSourceCodeNavigation::NavigateToFunctionSourceAsync(FString const&, FString const&, bool)::FNavigateFunctionParams, (ESPMode)0>, TSharedPtr<SNotificationItem, (ESPMode)0> >::ExecuteIfSafe(ENamedThreads::Type, TRefCountPtr<FGraphEvent> const&) const   [UnknownFile]) 
0x099ed42e UE4Editor-UnrealEd.dylib!TGraphTask<FDelegateGraphTask>::ExecuteTask(TArray<FBaseGraphTask*, FDefaultAllocator>&, ENamedThreads::Type)   [UnknownFile]) 
0x019b264c UE4Editor-Core.dylib!FNamedTaskThread::ProcessTasksNamedThread(int, bool)   [UnknownFile]) 
0x019b1ad8 UE4Editor-Core.dylib!FNamedTaskThread::ProcessTasksUntilIdle(int)   [UnknownFile]) 
0x019ad56e UE4Editor-Core.dylib!FTaskGraphImplementation::ProcessThreadUntilIdle(ENamedThreads::Type)   [UnknownFile]) 
0x04eee18a UE4Editor-Engine.dylib!FFrameEndSync::Sync(bool)   [UnknownFile]) 
0x0188e824 UE4Editor!FEngineLoop::Tick()   [UnknownFile]) 
0x01895252 UE4Editor!GuardedMain(wchar_t const*)   [UnknownFile]) 
0x018a2890 UE4Editor!-[UE4AppDelegate runGameThread:]   [UnknownFile]) 
0x01b40417 UE4Editor-Core.dylib!-[FCocoaGameThread main]   [UnknownFile]) 
0x9da248ad Foundation!__NSThread__start__()   [UnknownFile]) 
0xb1dc793b libsystem_pthread.dylib!_pthread_body()   [UnknownFile]) 
0xb1dc7887 libsystem_pthread.dylib!_pthread_body()   [UnknownFile]) 
0xb1dc708d libsystem_pthread.dylib!thread_start()   [UnknownFile]) 

SEGV_MAPERR at 0x3

UE4Editor-ApplicationCore.dylib!FMacErrorOutputDevice::Serialize()
UE4Editor-UnrealEd.dylib!FSourceCodeNavigationImpl::NavigateToFunctionSource()
UE4Editor-UnrealEd.dylib!FSourceCodeNavigation::NavigateToFunctionSourceAsync(FString const&, FString const&, bool)::FLocal::NavigateToFunctionSourceTaskWrapper(ENamedThreads::Type, TRefCountPtr<FGraphEvent> const&, TSharedRef<FSourceCodeNavigation::NavigateToFunctionSourceAsync(FString const&, FString const&, bool)::FNavigateFunctionParams, (ESPMode)0>, TSharedPtr<SNotificationItem,()
UE4Editor-UnrealEd.dylib!TBaseStaticDelegateInstance<TTypeWrapper<void> (ENamedThreads::Type, TRefCountPtr<FGraphEvent> const&), TSharedRef<FSourceCodeNavigation::NavigateToFunctionSourceAsync(FString const&, FString const&, bool)::FNavigateFunctionParams, (ESPMode)0>, TSharedPtr<SNotificationItem, (ESPMode)0> >::Execute()
UE4Editor-UnrealEd.dylib!TBaseStaticDelegateInstance<void (ENamedThreads::Type, TRefCountPtr<FGraphEvent> const&), TSharedRef<FSourceCodeNavigation::NavigateToFunctionSourceAsync(FString const&, FString const&, bool)::FNavigateFunctionParams, (ESPMode)0>, TSharedPtr<SNotificationItem, (ESPMode)0> >::ExecuteIfSafe()
UE4Editor-UnrealEd.dylib!TGraphTask<FDelegateGraphTask>::ExecuteTask()
UE4Editor-Core.dylib!FNamedTaskThread::ProcessTasksNamedThread()
UE4Editor-Core.dylib!FNamedTaskThread::ProcessTasksUntilIdle()
UE4Editor-Core.dylib!FTaskGraphImplementation::ProcessThreadUntilIdle()
UE4Editor-Engine.dylib!FFrameEndSync::Sync()
UE4Editor!FEngineLoop::Tick()
UE4Editor!GuardedMain()
UE4Editor!<Unknown>
UE4Editor-Core.dylib!<Unknown>
Foundation!Unknown()
libsystem_pthread.dylib!<Unknown>
libsystem_pthread.dylib!<Unknown>
libsystem_pthread.dylib!<Unknown>