Check if MyEntId isnt nil

[wrefgtzweve]

Fixes:

- addons/wire/lua/entities/gmod_wire_motor.lua:58: table index is nil
1. <unknown> - addons/wire/lua/entities/gmod_wire_motor.lua:58
 2. xpcall - [C]:-1
  3. CreateEntityFromTable - addons/advdupe2/lua/advdupe2/sv_clipboard.lua:1058
   4. <unknown> - addons/advdupe2/lua/advdupe2/sv_clipboard.lua:1334
    5. pcall - [C]:-1
     6. <unknown> - addons/advdupe2/lua/advdupe2/sv_clipboard.lua:1541
      7. <unknown> - addons/kaki/lua/includes/modules/hook.lua:335

This can happen if a malformed dupe or a gmod_wire_motor without a constraint is spawned.
gmod_wire_motor can exist without as constraint.Motor can return a nil if the constraint failed to be created.

[Astralcircle]

I think you can add check also here, i remember it errored too