So I ended up reinstalling my mdk and updated everything so it ran on 30.0.51, but I've ended up with the same crash.
I'll include the crash report below.
Should I be updating to 1.15.2 so I can use the latest mdk for that instead?
Terribly sorry - I must have missed your comment.
As it happens, I'm having trouble figuring out how to get my mod to run with the latest version, as its still running with 1.15.1 - 30.0.41
How do you update it properly?