End Portal teleporting to nether and subsequent nether portal teleporting out of world.

I tried to enter the End for the first time on a map I've been using for quite some time. I had the difficulty set to Peaceful. When I jump into the end-portal I got teleported to the Nether instead of the End but it spawned an obsidian platform just like it does in the end.

After locating one of my nether portals in the nether I try to exit the nether but it then teleported me out of the world where I died.

Worth noting is that this map also got corrupted a few days ago and I "fixed" it by creating a new map with the same name and replacing all the data in the save folder to the old save.

I have been playing this map to and from since the start of 2012 or so.