Replaced the old evolution lookup with a safe get_force_evolution_factor(enemy_force, surface) helper.
Moved the evolution check inside the surface loop, so each surface uses its own evolution value.
Wrapped explosive-biter spawn position lookup in pcall.
Wrapped explosive-biter creation in pcall.
Wrapped biter command assignment safely, so missing/changed commandable behavior should not crash the mod.
Wrapped explosive-biter explosion damage calls so a weird target entity should not crash the whole script.
