From what I can tell, this is an issue with Unity itself. An input device (RI stands for "Raw Input"), such as a gamepad or joystick, isn't being processed by Unity properly. I'm afraid I don't know of any way to fix it, it seems to be a common problem to Unity which occasionally turns up. If you had something new plugged in that might be causing it. Alternatively, it might be present all the time, but only development mode throws an error. If so, just wait for the next version and I'll release it as non-development, and that might fix things.