If an actor contains a custom SceneComponent that creates another component that is tagged with Transient and DuplicateTransient, deleting/un-deleting/deleting the actor again will cause the editor to crash.
This also causes the project to reach 95% when loading and then produce the same callstack.
Crash only seems to occur if the component that is declared in the custom scene component is marked as Transient and DuplicateTransient in its UPROPERTY macro.
Editor crashes when trying to delete the actor again.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-25780 in the post.