Errors occur when you block/unblock multiple users from user list.

The issue occurs when a user with the following permissions block or unblock multiple users:
Assign roles
Administer users
View user profiles

The user doesn't have the 'administrator' role assigned, the issue isn't reproducible with the 'administrator' role.

I selected two users and blocked them, the task has been completed successfully and they have been blocked but the following errors occurred:
Notice: Undefined offset: 1 in _roleassign_user_operations() (line 183 of ../roleassign/roleassign.admin.inc).
Notice: Undefined offset: 1 in _roleassign_user_operations() (line 183 of ../roleassign/roleassign.admin.inc).

Let me know if any additional information should be provided.
Thank you.