[ErrorProp]: Implements an error prop (fixes #693)

[aFarkas]

@lookfirst It took me a little bit longer but here is now the PR.

[CLAassistant]

All committers have signed the CLA.

[lookfirst]

@aFarkas Nice work! A couple things, I'd like resolved before merging.

1. centralize the common logic code to DRY things. for example, the takeText can be a function defined in util.
2. add unit tests for the TextField that tests these error conditions. those tests should then be copied to other components as well, but i can help with that if you need (or you can just do it).

Thanks again for your time and contribution, super appreciate it.

[aFarkas]

@lookfirst
I can earliest start working on it on 1. - 3. oct.

[lookfirst]

Thanks for the update @aFarkas! No rush... just when you have time. It isn't like this is paid open source... if someone else sees this and wants to contribute, feel free as well! =) This is a team effort here.

[lookfirst]

Pinging you @aFarkas