How odd, the game appears to be crashing trying to generate oil veins in your MystCraft age. I've not seen this before.
I've looked into old ways I used to know to wipe your player location and inventory. Fortunately, Minecraft is now a lot better protected against accidental deletion of player data. Unfortunately, when your player data is trying to put you in a broken location, it's really difficult to fix it. My old methods now make the world fail to load completely.
If you know the dimension number for the MystCraft age you were generating, one option is to wipe the save folder for that dimension and try regenerating the age.