Errors methods are not reactive

only the Errors methods flagged with `reactive` are reactive.

Thus if you say for example `some_record.errors.messages.keys.include(:some_key)`

and the error messages change, the code will never react!

Its not clear what we should do about this. Perhaps make all methods reactive?
just advise to prefix code like the above like this: `some_record.valid?` (because valid? does react and is based on the records Error object)