Issue recurring

After blocking a user, plugin fails for other recurrences.

This is the error when trying to create them:

rake aborted!
ActiveRecord::RecordInvalid: Validation failed: Assignee is invalid
/usr/local/bundle/gems/activerecord-5.2.4.2/lib/active_record/validations.rb:80:in `raise_validation_error'
/usr/local/bundle/gems/activerecord-5.2.4.2/lib/active_record/validations.rb:52:in `save!'
/usr/local/bundle/gems/activerecord-5.2.4.2/lib/active_record/transactions.rb:315:in `block in save!'
/usr/local/bundle/gems/activerecord-5.2.4.2/lib/active_record/transactions.rb:387:in `block in with_transaction_returning_status'
/usr/local/bundle/gems/activerecord-5.2.4.2/lib/active_record/connection_adapters/abstract/database_statements.rb:265:in `transaction'
/usr/local/bundle/gems/activerecord-5.2.4.2/lib/active_record/transactions.rb:212:in `transaction'
/usr/local/bundle/gems/activerecord-5.2.4.2/lib/active_record/transactions.rb:385:in `with_transaction_returning_status'
/usr/local/bundle/gems/activerecord-5.2.4.2/lib/active_record/transactions.rb:315:in `save!'
/usr/local/bundle/gems/activerecord-5.2.4.2/lib/active_record/suppressor.rb:48:in `save!'
/usr/src/redmine/plugins/issue_recurring/app/models/issue_recurrence.rb:389:in `block in create'
/usr/local/bundle/gems/activerecord-5.2.4.2/lib/active_record/connection_adapters/abstract/database_statements.rb:267:in `block in transaction'
/usr/local/bundle/gems/activerecord-5.2.4.2/lib/active_record/connection_adapters/abstract/transaction.rb:239:in `block in within_new_transaction'
/usr/local/bundle/gems/activerecord-5.2.4.2/lib/active_record/connection_adapters/abstract/transaction.rb:236:in `within_new_transaction'
/usr/local/bundle/gems/activerecord-5.2.4.2/lib/active_record/connection_adapters/abstract/database_statements.rb:267:in `transaction'
/usr/local/bundle/gems/activerecord-5.2.4.2/lib/active_record/transactions.rb:212:in `transaction'
/usr/src/redmine/plugins/issue_recurring/app/models/issue_recurrence.rb:373:in `create'
/usr/src/redmine/plugins/issue_recurring/app/models/issue_recurrence.rb:607:in `block (3 levels) in renew_all'
/usr/src/redmine/plugins/issue_recurring/app/models/issue_recurrence.rb:607:in `each'
/usr/src/redmine/plugins/issue_recurring/app/models/issue_recurrence.rb:607:in `block (2 levels) in renew_all'
/usr/src/redmine/plugins/issue_recurring/app/models/issue_recurrence.rb:606:in `each'
/usr/src/redmine/plugins/issue_recurring/app/models/issue_recurrence.rb:606:in `block in renew_all'
/usr/local/bundle/gems/activerecord-5.2.4.2/lib/active_record/relation/delegation.rb:71:in `each'
/usr/local/bundle/gems/activerecord-5.2.4.2/lib/active_record/relation/delegation.rb:71:in `each'
/usr/src/redmine/plugins/issue_recurring/app/models/issue_recurrence.rb:605:in `renew_all'
/usr/src/redmine/plugins/issue_recurring/lib/tasks/issue_recurring.rake:13:in `block (3 levels) in <top (required)>'
/usr/local/bundle/gems/rake-13.0.1/exe/rake:27:in `<top (required)>'
Tasks: TOP => redmine:issue_recurring:renew_all
(See full trace by running task with --trace)
W, [2020-05-11T19:38:53.248277 #17150]  WARN -- : Creating scope :sorted. Overwriting existing method Group.sorted.
W, [2020-05-11T19:38:53.283887 #17150]  WARN -- : Creating scope :sorted. Overwriting existing method User.sorted.
W, [2020-05-11T19:38:53.286140 #17150]  WARN -- : Creating scope :having_mail. Overwriting existing method User.having_mail.
W, [2020-05-11T19:38:53.694983 #17150]  WARN -- : Creating scope :system. Overwriting existing method Enumeration.system.
W, [2020-05-11T19:38:56.890503 #17150]  WARN -- : DEPRECATION WARNING: Using a dynamic :action segment in a route is deprecated and will be removed in Rails 6.0. (called from instance_eval at /usr/src/redmine/config/routes.rb:370)
W, [2020-05-11T19:38:56.892850 #17150]  WARN -- : DEPRECATION WARNING: Using a dynamic :action segment in a route is deprecated and will be removed in Rails 6.0. (called from instance_eval at /usr/src/redmine/config/routes.rb:370)
W, [2020-05-11T19:38:56.893680 #17150]  WARN -- : DEPRECATION WARNING: Using a dynamic :action segment in a route is deprecated and will be removed in Rails 6.0. (called from instance_eval at /usr/src/redmine/config/routes.rb:370)
W, [2020-05-11T19:38:56.894558 #17150]  WARN -- : DEPRECATION WARNING: Using a dynamic :action segment in a route is deprecated and will be removed in Rails 6.0. (called from instance_eval at /usr/src/redmine/config/routes.rb:370)
W, [2020-05-11T19:38:56.895411 #17150]  WARN -- : DEPRECATION WARNING: Using a dynamic :action segment in a route is deprecated and will be removed in Rails 6.0. (called from instance_eval at /usr/src/redmine/config/routes.rb:370)
W, [2020-05-11T19:38:56.896217 #17150]  WARN -- : DEPRECATION WARNING: Using a dynamic :action segment in a route is deprecated and will be removed in Rails 6.0. (called from instance_eval at /usr/src/redmine/config/routes.rb:370)
W, [2020-05-11T19:38:56.897019 #17150]  WARN -- : DEPRECATION WARNING: Using a dynamic :action segment in a route is deprecated and will be removed in Rails 6.0. (called from instance_eval at /usr/src/redmine/config/routes.rb:370)

after deleting the blocked user recurrences, the plugin begin working again.

thanks in advance !