To reproduce:

• Create a course with three activities by order (1, 2, 3, 4, 5)
• Open the app, go to the course and open activity 3
• Go back to the Moodle site as admin/teacher delete activity 2
• Go back to the app again, use the bottom navigation to go to activity 2
• An error is displayed

Expected outcome:

• Go to activity 1 or go to activity main course page if not previous activities