Pulp2 to Pulp3 content migration fails with error "NoMethodError: undefined method `repository_errata' for nil:NilClass"

Issue

• The satellite-maintain content prepare command fails with the following error:

  2022-10-20 10:20:22 +0000: Importing migrated content type erratum: 773000/771271Migration failed, You will want to investigate: https://satellite.example.com/foreman_tasks/tasks/0b1cd29e-2320-4d79-9d0b-d90da99f17c7
  rake aborted!
  ForemanTasks::TaskError: Task 0b1cd29e-2320-4d79-9d0b-d90da99f17c7: NoMethodError: undefined method `repository_errata' for nil:NilClass
  /opt/theforeman/tfm/root/usr/share/gems/gems/katello-3.18.1.55/lib/katello/tasks/pulp3_migration.rake:43:in `block (2 levels) in <top (required)>'
  /opt/rh/rh-ruby25/root/usr/share/gems/gems/rake-12.3.3/exe/rake:27:in `<top (required)>'
  Tasks: TOP => katello:pulp3_migration
  (See full trace by running task with --trace)
                                                                       [FAIL]
  Failed executing preserve_output=true foreman-rake katello:pulp3_migration, exit status 1
  

• The satellite-maintain content migration-stats command displays few missing or unmigrated Contents as shown below:

  ================================================================================
  Retrieve Pulp 2 to Pulp 3 migration statistics:
  ============Migration Summary================
  Migrated/Total RPMs: 247864/248794
  Migrated/Total errata: 1263335/1283802
  Migrated/Total repositories: 1185/1193