Add Descriptive Error Variants

[calebbourg]

Currently we use an Other variant in various places throughout the application. This was done intentionally as the app was evolving so as to not add variants ad-hoc. Now that the app is maturing, it makes sense to take inventory of these and add some more descriptive variants. There's a potential for Other to hold a string value as well to provide a way to include extra context for 1 off errors.

[jhodapp]

@calebbourg still relevant to keep around or have you reached a level that you're happy with now?