I have recently started a Single Player world, and spawned in a swamp right next to a plains biome. I spotted a tree, so like usual, I cut it down. However, the tree was too big for my reach distance to actually finish cutting down the whole tree, so I placed a Wooden Log (Oak) on top of where I was standing, and the game crashed. Not further could it be evidence within itself, I decided to try it again, and the same thing happened. However, when it happened the 3rd time, my world got removed from the Single Player list. On this single player world I toggled the /gamerule naturalRegeneration to false, and then started cutting down the trees.