While testing MDL-54751, it was observed that, the user can click on cog icon and go to edit grade page for deleted activities. Although the changes are not saved, it would be nice if this don't happen.

Steps to reproduce:

1. Make sure you have at least one activity somewhere in the course. Remember the name.
2. Run cron to make sure all adhocs have been run.
3. Check the gradebook pages (gradebook setup, reports etc) and Confirm that no warning notification is present on the pages.
4. Click 'Grader report'
5. Turn editing on
6. Confirm that you can edit the grades inline for your activity from (1)
7. Now, go back to course home page and delete the activity, but don't run the cron task.
8. Now, check the gradebook pages again. Confirm that you see the 'Activity deletion in progres' warning. Check all pages in the menu.
9. Click the grader report again and enable editing (if not already enabled)
10. Confirm that:
    • The activity you just deleted is still listed, but with a '[Deletion in progress] ' string prepended to its name.
    • You can't inline-edit the grades for this activity (grade items are locked)
11. Now click on cog icon next to deleted activity and it will take you to edit grade page. This should not be happening.
12. Go back to Grader report and click on pen icon next to activity and you will be taken to single view page, and allowed to edit the grades. Although grades are not saved, but all message show that grades are being saved.