I’m also switching my game from 5.2 to 5.3 and in 5.3, I have the same error in my developement build as well. Exact same call stack. Strange thing is, it’s makred as “Handled”, so the game should not crash on it. It should crash on a UnHandled ensure.
So I built the DebugGame build. And sometimes it crashes with this mode, and sometimes not.
I also find out the Developement build dosen’t crash 100% of the time. If I spam the .exe, at one moment, it will pass. 
Once it passed, it will work 100% of the time for a moment.
Have you the same behavior ?