When using the Migration system there are many migration_map and migration_message tables created in the db. As discussed in https://www.drupal.org/node/2713327 these never get deleted. People might delete some of these tables by hand or using another method. If these tables are missing you cannot rollback a migration, the rollback fails with an SQL exception.
I would propose that we be more lenient and try to continue after a delete call to a missing migration table. When you run a migration these tables are (re)created automatically.