if you try to mine landfill while any of spidertrons legs are on the block, spideyboi will vanish. This happened when I had the spidertron extended mod, not sure if that matters.

Thanks for the report.
That is sadly how removing tiles under entities works. And it used to happed to every entity before version 1.0.5 but fixing it for moving entities like vehicles is more tricky (especially spidertron) and I don't know how to fix it. For now keep your spidertron away from landfill that you want to mine.
Have a great day!

That makes sense, I am relatively new to factorio and am unaware of many of those little mechanics and wasnt sure if it was just a small bug or not. luckily I saved probably like 10 seconds before it happened and have been able to avoid it easily since it happened. Great job on the mod man, and thank you for the response <3