Validate if the element has valid color before saving

Fixed. Merge request with that is available at: https://git.drupalcode.org/project/openchurch_theme/-/merge_requests/1

Implemented the suggestions at #4 and #5

Verified the MR!1 on Drupal version 9.5.x and OpenChurch Theme version 3.0.x. The patch applied cleanly and now an error message is displayed when an invalid color code is given n the 'Link Color' field. I have added the before and after screen recordings for reference.
Just one more concern:- The text font color of that field is always white. Is it expected to be like that? Because if we put some invalid color in that field and try save the configuration, then the background color of that field will be white which makes it difficult to read the text given in that field (Please refer screen recording for more clarity.)

The text font color of that field is always white. Is it expected to be like that?
makes it difficult to read

I also see that, but I think is a different issue. So I reported at 🐛 Font color in white is card to read Fixed

Automatically closed - issue fixed for 2 weeks with no activity.