The UI seems a bit broken. I entered some airport codes, and chose dates, but it was not until the next screen that I was told "An error occurred" and neither

The UI seems a bit broken. I entered some airport codes, and chose dates, but it was not until the next screen that I was told "An error occurred" and neither airport is "supported". I had to click Back to proceed, and completely lost my original query. It should tell me as soon as I enter my airport codes if they are not supported. Also, on https://levelskies.com/flights/ https://levelskies.com/flights/ I clicked "Add my city", filled out the popup form, and it refused to submit the feedback form because the underlying search form fields were not completed. Seems like more thorough UI testing is needed.