attempted to call Gettable (a nil value)

[Enzyme²]

Bit confused onto how to fix this or what it means, any and all help is appreciated.
(this is a script to freeze cars)

[ERROR] lua/autorun/car_freeze.lua:46: attempt to call field 'GetTable' (a nil value)
  1. fn - lua/autorun/car_freeze.lua:46
   2. unknown - addons/ulib/lua/ulib/shared/hook.lua:109

The first bit of code mentioned in the error

43 hook.Add("PhysgunDrop", "car_freeze_drop", function( ply, ent )
44 if(!ent:IsPlayer()) then
45 if(ent:GetClass() == 'prop_vehicle_jeep') then
46 for k, v in pairs (constraint.GetTable(ent)) do
47 if(v.Ent2 == game.GetWorld()) then
48 v.Constraint:Remove();
49 end;
50 end;
51 -- ent:SetMoveType(6)
52 -- local phys = ent:GetPhysicsObject()
53 -- if phys:IsValid() then phys:SetDamping(0, 0) end
54 -- local ConstrainedEnts = constraint.GetAllConstrainedEntities( ent )
55 -- for _, ent in pairs( ConstrainedEnts ) do
56 -- if(ent.Entity:IsValid()) then
57 -- ent.Entity:SetMoveType(6);
58 -- end;
59 -- end;
60 end;
61 end;
62 end);

2.
92 function Call( name, gm, ... )
93
94 --
95 -- Run hooks
96 --
97 local HookTable = Hooks[ name ]
98 if ( HookTable != nil ) then
99
100 for i=-2, 2 do
101
102 for k, v in pairs( HookTable[ i ] ) do
103
104 if ( v.isstring ) then
105
106 --
107 -- If it's a string, it's cool
108 --
109 local a, b, c, d, e, f = v.fn( ... )
110 if ( a != nil && i > -2 && i < 2 ) then
111 return a, b, c, d, e, f
112 end

[SneakySquid]

car_freeze.lua is a shared file and PhysgunDrop is a shared hook but constraint.GetTable is a serverside function.