I would think that having no cart slot on any system would be the same as not having a game inserted.
Some systems like the gamecube ony give error when the DVD drive is disconnected because I think it's part of the boot process and needs to be persistent at the GC menu when you do insert a game. The error is there to give feedback to the person running the program that something is wrong with the connection or some other baloney (this goes for all programs and OSes really)