Exception Reading level.dat: loading NBT data

Expected Result
To be seen in Singleplayer worlds screen
 
Actual Result
Not present in UI
 
Steps to Reproduce:

I am not sure how this happened, I'm guessing just world issues with 18w19b. Yesterday it was alright, and today after opening the game, I opened the log and saw this when it tried to get the worlds from the saves folder.

 

Crash Report can be found below