Negative number of lemmings error when there are zombies [MAJOR BUG][EXP-PLAYER]

[Wafflem]

Player: V10.13.16:3256064

In any zombie level, whenever I open up a level and the lemmings start exiting the hatch, I get this error (displayed in the picture below). Afterwards, the player crashes, and even if I click "OK", the error refuses to go.

[namida]

I've fixed the crash already. However, a bug still remains where, if any zombies are going to spawn from hatches, they are counted as alive (in the "alive lemmings" count) until they actually do spawn.

[namida]

Fixed that too now.