Crash from Tmap removing a key then printing the remaining keys

Crash from Tmap removing a key then printing the remaining keys. This has occurred in the third person template, but no further testing has been done for other templates.

Regression:
TMaps did not exist before 4.15 so this is an issue from 4.15 on

1. Create a new project using the third person template
2. Create a new struct > name it "String_Struct" > Open String_Struct
3. Modify the struct so it has 3 string variables > Save and close String_Struct
4. Create a new actor class blueprint > name it "Actor_BP" > Open Actor_BP
5. Create the blueprint from Screenshot_01
6. Add Actor_BP to the level
7. PIE
   Result: Editor Crashes
   Expected result: Editor does not crash and prints the key

UE4Editor_Core!rml::internal::Block::findObjectSize()
UE4Editor_Core!FMallocTBB::Realloc() malloctbb.cpp:73
UE4Editor_Core!TArray<wchar_t,FDefaultAllocator>::ResizeForCopy() array.h:2281
UE4Editor_Core!TArray<wchar_t,FDefaultAllocator>::operator=() array.h:419
UE4Editor_Core!FString::operator=() unrealstring.h:1700
UE4Editor_CoreUObject!TProperty<FString,UProperty>::CopyValuesInternal() unrealtype.h:1017
UE4Editor_Engine!UBlueprintMapLibrary::GenericMap_Keys() blueprintmaplibrary.cpp:57
UE4Editor_Engine!UBlueprintMapLibrary::execMap_Keys() blueprintmaplibrary.h:227
UE4Editor_CoreUObject!UFunction::Invoke() class.cpp:4525
UE4Editor_CoreUObject!UObject::CallFunction() scriptcore.cpp:721
UE4Editor_CoreUObject!UObject::ProcessContextOpcode() scriptcore.cpp:2149
UE4Editor_CoreUObject!UObject::ProcessInternal() scriptcore.cpp:948
UE4Editor_CoreUObject!UObject::CallFunction() scriptcore.cpp:845
UE4Editor_CoreUObject!UObject::execVirtualFunction() scriptcore.cpp:2255
UE4Editor_CoreUObject!UObject::ProcessInternal() scriptcore.cpp:948
UE4Editor_CoreUObject!UFunction::Invoke() class.cpp:4525
UE4Editor_CoreUObject!UObject::ProcessEvent() scriptcore.cpp:1318
UE4Editor_Engine!AActor::ProcessEvent() actor.cpp:678
UE4Editor_Engine!AActor::ReceiveBeginPlay()
UE4Editor_Engine!AActor::BeginPlay() actor.cpp:3129
UE4Editor_Engine!AActor::DispatchBeginPlay() actor.cpp:3097
UE4Editor_Engine!AWorldSettings::NotifyBeginPlay() worldsettings.cpp:183
UE4Editor_Engine!AGameStateBase::HandleBeginPlay() gamestatebase.cpp:177
UE4Editor_Engine!UWorld::BeginPlay() world.cpp:3435
UE4Editor_Engine!UGameInstance::StartPlayInEditorGameInstance() gameinstance.cpp:338
UE4Editor_UnrealEd!UEditorEngine::CreatePIEGameInstance() playlevel.cpp:3420
UE4Editor_UnrealEd!UEditorEngine::PlayInEditor() playlevel.cpp:2515
UE4Editor_UnrealEd!UEditorEngine::StartQueuedPlayMapRequest() playlevel.cpp:1215
UE4Editor_UnrealEd!UEditorEngine::Tick() editorengine.cpp:1522
UE4Editor_UnrealEd!UUnrealEdEngine::Tick() unrealedengine.cpp:391
UE4Editor!FEngineLoop::Tick() launchengineloop.cpp:3025
UE4Editor!GuardedMain() launch.cpp:166
UE4Editor!GuardedMainWrapper() launchwindows.cpp:134
UE4Editor!WinMain() launchwindows.cpp:210
UE4Editor!__scrt_common_main_seh() exe_common.inl:264
kernel32!<Unknown>
ntdll!<Unknown>