Erasing the outer walls crashes the simulator

[MartinKist]

Pretty much what the title says :)

Idk why i had so much fun dropping some food and building some obstacles and seeing these little virtual ants building an ameisenstraße (looks to me like there is no term for this phenomenon in english).
Nice work 👍

[johnBuffer]

Thank you for this!
It's because I didn't implement any checks at the map's boundaries so it segfaults when trying to sample markers from outside the world. I was relying on walls to prevent this from happening but forgot that they can be removed :D
Will add a fix for this.

[johnBuffer]

Fixed in master