Should error tuples return exception atoms or structs?

[XavKearney]

Currently in GSS.Spreadsheet, the type @type spreadsheet_response :: {:json, map()} | {:error, Exception.t} | no_return() specifies that functions return an error tuple with an Exception struct.

However, in the code (e.g. here), the return value is actually {:error, GSS.GoogleApiError} where GSS.GoogleApiError is an atom corresponding to the module and not the struct %GSS.GoogleApiError{}.

I submitted a PR here which corrects some of the instances of Exception.t to be atoms so that dialyzer is able to correctly type check. This isn't a complete solution - it may be better to convert all of the returns to the respective struct if that is what was intended.