Warning: Undefined array key "node_type" in workbench_moderation_migrate.module on line 80

An example of a migration which triggers this behaviour is a migration which has a source plugin of "content_entity:node" and shares a site with migrations using Workbench Moderation Migrate (eg "d7_node_complete" or derivatives.

The relevant block of code is https://git.drupalcode.org/project/workbench_moderation_migrate/-/blob/6...

"content_entity:node" is a source which Workbench Moderation Migrate should skip. The array filter finds migrations with a destination of "entity_complete:node", but does not realise that the source is not either "d7_node_complete" or a derivative thereof.

The current behaviour was to set $node_type to NULL (which means no workflow will be found), and this MR retains that but does it explicitly.

MR!4 includes both fix and changes to make the behaviour show up with tests.

MR!5 has only the test changes (adding some migrations which trigger this behaviour when run through workbench_moderation_migrate_migration_plugins_alter(), which shows up in tests output).