CLASS_GROUP Does Not Exist

[KhoonSun47]

The issue is on what if the CLASS_GROUP does not exist and does not have a student in it?

Currently, the user can view CLASS_GROUP that he/she is not teaching, with no student in it.

This could provide inconvenience on the user because he/she should only view the CLASS_GROUP that he/she is responsible for, or not the user will wonder on why he/she have this specific CLASS_GROUP with no student in it, leading to confusion.

For example:

Current Input:

• ls 12

Current Output:

• Listed 0 students from class groups: 12

Expected Output:

• Class group do not exist.

Is it possible to validate whether the CLASS_GROUP exist?