this problem happened using the FTB Mod
In options during the game I was changing from 'peaceful' to 'easy' to spawn mobs when it crashed
Steps to Reproduce:
Can't get back into the game because now on opening the world, it crashes!
Sending 2 crash reports
1st crash was the initial one. 2nd crash is my attempt to get back into the game.
This ticket is invalid as it relates to a modified or 3rd party client, server, or launcher.
Any non-standard client/server/launcher build needs to be taken up with the appropriate team, not Mojang.
Any plugin issues need to be addressed to the plugin creator.
This site is for addressing issues related to the base unmodded Minecraft.