I was riding to my ender farm on a minecart track in the end, the track is 3 blocks wide one block for the roof and one block for the floor. I hit shift to get out of the cart and fell out of the world, losing everything. I went back to enchant new stuff, I had to walk to the farm since the cart was at the other end, on my way returning I hit shift and fell out of the world. For a lot of the track the walls are a slab at the bottom and top, allowing a natural window but not enough space to walk out but I don't think it had to do with the slabs because on my return I am in a 1x2 box of solid snow blocks. This has not happened before this snapshot.