NoMethodError exception in SchoolStudent::List#list_students

[chrisroos]

While clearing out exceptions for experience-cs I noticed this exception in editor-api which appears to reveal a bug in the code:

NoMethodError

undefined method `id' for nil:NilClass (NoMethodError)

        ProfileApiClient.list_school_students(token:, school_id: school.id, student_ids:).map do |student|
                                                                       ^^^

The error is caused when the school passed in to #list_students is nil, which appears to be possible because of this line in Project.users. The pluck(:school_id) returns an array of all school_ids for the current Project scope. My guess is that in some cases the first entry in the array of school_ids is nil, which means we execute School.find_by(id: nil) which returns nil. An alternative guess is that the school_id isn't nil but somehow doesn't correspond to an ID in the schools table. I think the second guess is less likely due to the foreign key constraint on projects and schools but I don't know for sure.

[chrisroos]

Flagging this for your attention, @adrian-rpf. There are 18k instances of this in Sentry so it might be worth investigating (assuming you haven't already) in case it's causing a real problem for users.

[create-issue-branch]

Branch bugfix/548-NoMethodError_exception_in_SchoolStudent_List#list_students created!