Laravel - Way to use `->map()` in conjunction with `->firstOrFail()`?

I'm using the ->map() function as demonstrated in this SO question, but now I need to update the scopes that use ->firstOrFail() instead of ->get(). Or if you cannot use ->map() with ->firstOrFail(), how can I edit some of the values on the fly when using a scope to fetch an individual record?

via Chebli Mohamed