Error Handling and Recovery

If one clicks the DISK gadget before amigados has mounted the disk in DF1, an AmigaDos requester will appear saying there's no disk in drive 1. Ignore it; the requester should go away after a few seconds. If the user clicks the DISK device more than once between disk swaps, the same disk will be cataloged multiple times. This is wasteful of operator time and of space on the catdisk.