ok i found out that it crashes only when i place the turret within the area of electricity, it doesn´t when it´s outside. and it crashes when the shield is full, i got the error by saving the game (server game) and opening it in single player.
Error while running event Turret-Shields::on_tick (ID 0)
Unknown entity name: liquid-square-14
stack traceback:
Turret-Shields/on_tick.lua:337: in function <Turret-Shields/on_tick.lua:1>
stack traceback:
[C]: in function 'create_entity'
Turret-Shields/on_tick.lua:337: in function <Turret-Shields/on_tick.lua:1>