[Fyron]

I believe that should no longer be a problem in 1.91. It was fixed when the mine algorithms were changed to prevent a high structure component, such as a colony module, from causing all mine warheads that did not do enough damage in one hit to destroy it to not detonate. If no engines are left, no engine-damaging mines should detonate. I have no idea what happens if you mix warheads on the same mine unit, however.