Using UE 4.9.1. I was trying to move an object into a folder in the World Outliner, and hit a crash on the line
for (auto* ChildComponent : InActor->GetRootComponent()->AttachChildren)
in TraverseActorTree_ParentFirst() in ActorEditorUtils.cpp.
If I had Git set up, I’d submit my fix, but I don’t, so, my fix is to change the first line of that function to:
if ((!InActor) || (!InActor->GetRootComponent()))
{
return true;
}