Fix modular car conditional object NRE that could occur when adding a new module to a chassis, if the following out-of-order scenario occurred:
- Server creates the module entity and saves it to client with socket index -1 (no socket)
- Server adds the module to the car with socket index now set
- Server saves new socket index to client
- Client creates the module entity and calculates socket index correctly
- Client loads new entity, socket index incorrectly reverts to -1
- Client refreshes module conditionals, bad socket index causes NRE