Here's the world as a zip file.
The issue described there doesn't seem to match mine, since there seems to be no pop-up for me. However it could very well provide a solution, which I will investigate now.
Edit: Upon testing the solution supplied in MCL-2628, I was unable to get my launcher working and am still hit with the same issue as before.
Edit2: After looking at MCL-1049, this seems to be an effective work around for the issue I'm having.
Edit3: Scratch that, upon clicking play the launcher will close down, stopping the entire process including the game.
The crash report has been attached also.