Madcow weapons Npc support

Can u make madcow weapons for npc that can shoot. It used to shoot but not anymore after the few updates that garry installed >:(( but anyways here is the error i have

[addons\mad cows weapons\lua\weapons\weapon_mad_base\shared.lua:640] attempt to call method ‘GetViewModel’ (a nil value)
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any ideas of how to fix that?