It is fixable, simply edit your player.dat or level.dat, locate the player status effect "0" and change the zero to "1"Had a friend report this same issue in a SP world he started a few weeks ago. Dismissed it as a one off, but it was the exact same scenario. He encounterned a Trents (one of the big ones) hit it twice and the game crashed. He was not able to get back into it. If he still has it I will have him try and delete the player.dat and see what happens.