PostCode component - rethink

[smellyshovel]

Originally taken from #5

How should I handle the post code field in the settings?

pc.mp4

Sometimes it shows the error message, sometimes it doesn't. Moreover, there's no indication of whether there's an error in the outside component. The only available context is whether there's something selected or not. Where should I add a message saying that it's unable to save because it's invalid? To the right of the input? Or it's better not to touch it?

Originally posted by @smellyshovel in #5 (comment)