So one of the people on my mod's dev team told me that the server crashes by java.lang.NoClassDefFoundError: net/minecraft/client/entity/EntityPlayerSP and I have no idea what is causing that crash and how to fix it. It doesn't crash on my computer.
I've fixed it so the function returns ItemStack.EMPTY since I recently found that out before you told me and the model is rendering from the MobileSuit.MSRenderer class. Also, I didn't make the model, the model designer member made it.
The entity.render package is for non-Mobile Suit type entities. com.spaceboyross.gundam.models.ms.gundams.RX782GundamMobileSuitModel is the RX-78-2 Gundam Mobile Suit model class. So the com.spaceboyross.gundam.models.ms package is for the models for Mobile Suits.
This is what the model is supposed to look like.
But this is what it looks like in game.
The class of the model is com.spaceboyross.gundam.models.ms.gundams.RX782GundamMobileSuitModel. I have the mod stored on github: https://github.com/SpaceboyRoss01/MSGundamMod
Now I can't even interact with the entity. So I can't fix the movement until I fix interaction handling, all of a sudden the interaction function stopped working.