Confirmation is required when a user tries to delete all the messages/alerts.
I am working on this bug at https://bugs.launchpad.net/inkscape-web/+bug/1649744 Here is the info as on launchpad.
Title : There should be a confirmation dialog before 'delete all messages' deletes all messages
Description : Currently, all messages are deleted without requiring any confirmation.
Accidental deletion of messages is a possibility. Just happened to me.