The game crashed whilst ticking entity Error: java.lang.NullPointerException: Ticking entity

Same for me, game spawned duplicate llamas for the wandering merchant, game kept crashing until deleted with nbtexplorer

Thanks Oscar.  What did you delete with nbtexplorer?  Did you delete the entire save or where you able to delete the duplicate llama?  I've downloaded nbtexplorer but I'm not sure what to do next.  Thanks in advance.