[FEATURE] [BACKEND] Descriptive error messages

[proverbial-ninja]

Describe the user story:

Back end should return more descriptive error messages

Tasks (where applicable)

• [ ] eg. Fetch users end point

Tests (where applicable)

• [ ] eg. Passing Tests for x

Acceptance Criteria

• [ ] eg end-point " api/users" should not list users for non-admin users
• [ ] eg end-point " api/users" should list users for admin users

Screenshots where applicable