Ahh, I've just been crashes right after embark, every time, as reported by megahelmet. DiggingInvaders was set to off both in the init and something I personally checked before playing. Luckily I've worked out what causes this one:
My issue with crashing consistently after embark is problem with workflow settings left over from an earlier dwarf fort in the region I abandoned. I tried playing as dwarves on the same embark square my warlocks were going to and they did fine, only a few seconds after unpausing I got some error messages about 'unable to resume sand production' and 'unable to resume compact peat production'. I have set multiple playable races btw. Reclaiming my old fort with dwarves and deleting all the workflow constraints that were still there using CTRL-i and then disabled workflow in dfhack with workflow disable. I was able to embark and play as warlocks past the first few seconds.
Massive Edit: Looks like I jumped the gun, I didn't save it the one time it worked because I didn't prepare the embark properly for testing purposes and I'm back to crashing a few seconds after embark. Managed to embark in another region/save but it's worrying. I have changed the raws in this region increase the number of warlocks at the start.