some thing is wrong script errors please help

[Lennys]

this is error code

[ERROR] lua/weapons/weapon_fists.lua:207: Tried to use a NULL entity!
1. LookupSequence - [C]:-1
2. unknown - lua/weapons/weapon_fists.lua:207

i cant see my fist in dark rp and when i try to use my grav gun the game crashes