How can I validate a safelink before the user saves a variable in a SAIL FORM?..

I meant:
How can I validate a WebPage as a text to be shown later as a safelink before the user saves the variable in a SAIL FORM? The problem is that when the user saves an invalid webpage, the whole UI crashes. This is an ugly user experience.

Can you please clarify exactly what validation you want to make?

I validated that the web address does begin with a valid protocol (http://, or https://) and now the safelink function renders always well.

Thank you.