K, thanks for the help.
Understood. Much appreciated.
Thank you for your response, and sorry for not attaching crashing reports, here you go. I uploaded them in the thread.
I tried to load the crashed world after the first crash three times, so here's a total of four reports.
Confirmed. Some worlds from the previous snapshot can be loaded properly, but the world that already in pre-release 1 version can no longer be loaded again.