Just to update on my own troubleshooting, I created a mod to populate the trivial-smoke prototypes up to ID 100 with dummy prototypes mostly out of curiosity not expecting to actually fix the save but more to see what other errors there might be. I then got an error about a trivial-smoke with ID 255 ...

Hi, I can't load this map or any of the 3 autosaves, all give the above error.

I've attached the log file and the main save as well as a crash dump file from a bit earlier than the saves.

Any help would be greatly appreciated, thanks