the dreaded bomb with the numerical error code was a very compelling way to say something is wrong.....
Sometimes you could get out of that by getting into the debugger and typing "G FINDER". Usually you were screwed. Ah the joys of unprotected memory addresses.
Random anecdote: In order to run MultiFinder on my 1MB Macintosh Plus I had to hack the System file resources with ResEdit. For those that don't know, ResEdit was a tool that came with the Macintosh which allowed you to edit the resource fork of files. Back then, Mac files had a resource fork and a data fork. The resource fork held all the metadata for the file, such as icon and other graphics. There were benefits to that, but trying to share files with Windows users was always a disaster.