implement the Error interface

[radkomih]

There are places where we return values such as for eaxmple (Address32, TransactionValidityError), but there may be other errors that could occur and we might want to propagate them as well. For this reason, we might consider implementing the Error interface for all types that resemble errors (TransactionValidityError, TokenError, etc.).
In certain places, we should check if the error is of the type in which we are interested.

[tgntr]

as a next step we could remove Result types (e.g. goscale.Result, DispatchResultWithPostInfo)