fix(course user index): fix error when an admin user is not registered as a course user
fix(course user index): fix error when an admin user is not registered as a course user

Coursemology/coursemology2,Coursemology/coursemology2,Coursemology/coursemology2,Coursemology/coursemology2,Coursemology/coursemology2,Coursemology/coursemology2,Coursemology/coursemology2