Error message for missing users and roles in linkahead_admin.py

Summary

Added error messages when retrieving and updating an user or role with linkahead_admin. Addresses #200 (closed)

Focus

The code changes are in the second diff version, the other changes are exclusively indentation fixes for docstrings. Would it be useful to also add success messages for operations that do not print anything?

Check List for the Author

• All automated tests pass
• Reference related issues
• Not necessary: Appropriate user and developer documentation for new code
• Annotations in code

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• Appropriate user and developer documentation for new code
• The intended behavior is reproducible

src/linkahead/utils/linkahead_admin.py

@@ -33,7 +33,7 @@ from argparse import ArgumentParser, RawDescriptionHelpFormatter
 
 import linkahead as db
 from linkahead import administration as admin
-from linkahead.exceptions import HTTPClientError
+from linkahead.exceptions import HTTPClientError, HTTPResourceNotFoundError
 
 __all__ = []
 __version__ = 0.3
@@ -50,7 +50,10 @@ def do_create_role(args):
 
 
 def do_retrieve_role(args):
-    print(admin._retrieve_role(name=args.role_name))
+    try:
+        print(admin._retrieve_role(name=args.role_name))
+    except HTTPResourceNotFoundError:
+        print(f"Error: Role '{args.role_name}' does not exist.")
 
 
 def do_delete_role(args):
@@ -185,7 +188,10 @@ def do_set_user_email(args):
 
 
 def do_retrieve_user(args):
-    print(admin._retrieve_user(name=args.user_name))
+    try:
+        print(admin._retrieve_user(name=args.user_name))
+    except HTTPResourceNotFoundError:
+        print(f"Error: User '{args.user_name}' does not exist.")
 
 
 def do_delete_user(args):
@@ -193,11 +199,17 @@ def do_delete_user(args):
 
 
 def do_retrieve_user_roles(args):
-    print(admin._get_roles(username=args.user_name))
+    try:
+        print(admin._get_roles(username=args.user_name))
+    except HTTPResourceNotFoundError:
+        print(f"Error: User '{args.user_name}' does not exist.")
 
 
 def do_retrieve_role_permissions(args):
-    print(admin._get_permissions(role=args.role_name))
+    try:
+        print(admin._get_permissions(role=args.role_name))
+    except HTTPResourceNotFoundError:
+        print(f"Error: Role '{args.role_name}' does not exist.")
 
 
 def do_grant_role_permissions(args):