When deleting a dashboard you are redirected to the login screen. This is due to the user not being a part of the 'Jira User Global permission' group. The user is belongs to the 'jira-administrators' group and does not belong to the 'jira-users' group. Also, the user is able to login to JIRA without any issues. According to the definition of the JIRA User permission:

JIRA Users
Ability to log in to JIRA. They are a 'user'. Any new users created will automatically join these groups, unless those groups have JIRA System Administrators or JIRA Administrators permissions.
Note: All users need this permission to log in to JIRA, even if they have other permissions.

Nothing shows up in the log files. A friendly message should be displayed to the user.