I recently came across an error that looked like this:
'g_findconfigstringindex: overflow (2690): ' craftable_pap_1_shader'

This was on the Spongebob: Battle for Bikini Bottom map on coop online with some friends and I noticed some others had some issues as well. Listed are the solutions gathered:

1. Disable shaders that are causing the problem (if you are working on a map)
2. Check for extra files you have added (mod menus, hacks, textures, etc.)
3. Make sure you have the map fully updated (current update is 1.1 for Battle for Bikini Bottom)