Its normal that the error occurs. I previously thought that you could boot games and official channels without a disc drive and I had fought it with people because I thought that I had removed the drive in my wii that my family uses, but many months later I had opened up my wii and I found that I did in fact still have my drive in there. At this point I tested it out and removed the drive and tried booting a bunch of things and only homebrew would boot.
So that leads me to wonder, where the fuck did I get this extra drive that I still have on my desk.
But also, if you use a WODE then you can have the main WODE pcb attached to the wii and you won't need to use the normal drive at all. I haven't tested this with other modchips yet, but I doubt that they will work.