Just attach gdb to the process and wait for the crash directly there. If you really want to have crash dumps you should first enable them. Each distro has it's own way so go check out the reference.
Edit: OK, I found the issue with the original Metamod - it does not export all entities that are required for Gunman Chronicles regardless that on the metamod.org site it says that the mod is supported. Some entities are not spawned because of that and so "sprites/muzzleflash3.spr" is not precached on time, the engine tries to use it later when the bots begin to fight but it cannot find it, so it tries to precache it by himself but because of bug in the engine itself you get this error. So basically you will have to make Metamod-p a requirement. I will check later the Linux issues.