Wrong message received when deleting a page from an extension

Steps to reproduce:

1. Go to Sandbox.TestPage1
2. Click on Actions and then on Delete
3. Click "Yes, please delete this page"
4. Don't select any page and click on Delete

Actual result:
Sandbox.TestPage1 is NOT deleted and you get a message saying: The page has been deleted.

Expected result:
You should get a message telling you to select at least one page before clicking Delete.