Sorry, I'm not being clear. STR:

1. Add a new image event
2. Change the linkUrl to something valid, like `http://google.ca`
3. Change the linkUrl to something invalid like `javascript:alert(1)` or a blank string. Notice how you get the error message even if there's a blank URL?
4. Load another event, then load the original image event. See how it's the original valid value?

I don't know whether it'd be better to allow users to input invalid URLs and just show an error message or if we should remove invalid URLs, but we should allow inputting `""` to clear the linkUrl.