Right now, an error of that kind looks like this:
"DllNotFoundException: Assets/Plugins/XInputInterface.dll
XInputDotNetPure.GamePad.GetState (PlayerIndex playerIndex, GamePadDeadZone deadZone)
XInputDotNetPure.GamePad.GetState (PlayerIndex playerIndex)
InputHandler.UpdateRumble (Single deltaTime) (at Assets/Scripts/Core/InputHandler.cs:812)
InputHandler.Update () (at Assets/Scripts/Core/InputHandler.cs:869)
"

This is misleading, since the dll file exists in the project. We should detect that this is a 32 bit dll and inform the user that they need to either use a 32 bit Editor or switch the dll with a 64 bit one.