How to fail an instructor task

When some InstructorTasks are stuck (e.g. generating a csv for days in Pending), some tasks can be marked "FAILED" so that new tasks of that type can be created for that course.
NOTE: Here be dragons! Support has experience failing .csv reports, email, and grading tasks, but we don't know the impact of handling the full range of instructor tasks. Reach out to Aperture if there are certificate tasks at issue.

Step-by-step guide

1. Get the task id you're going to fail from the instructor dashboard: courses.edx.org/courses/<course_id>/instructor
2. Go to the django admin panel at https://courses-internal.edx.org/admin, and click "Instructor tasks", which is below "Instructor_Task"
3. Find the instructor task you want to fail
4. Set the Task state to "FAILURE" (all caps)
5. Set the Task output to "{}"
6. Set the Task key to "dummy_task_key"
7. Click Save

It is also possible to fail instructor tasks in bulk: 

https://github.com/edx/edx-platform/pull/25461