Handle failing foreign key additions

[mamhoff]

Summary

We've added some foreign key constraints recently, and have since come up with a nicer way of guiding users towards fixing their data intentionally.

This change gives them a nice error message and allows them to change the migration to remove offending records.

Co-Authored-By: [email protected]

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[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 88.97%. Comparing base (55a1be5) to head (55dd557). Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6293   +/-   ##
=======================================
  Coverage   88.97%   88.97%           
=======================================
  Files         861      861           
  Lines       18416    18416           
=======================================
  Hits        16386    16386           
  Misses       2030     2030           

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