refac: missing user or article is reported with a domain not-found error instead of a raw GORM error, and the API answers 404 for it

test/user_test.go

@@ -34,7 +34,7 @@ func (m *mockUserRepo) Get(id uint32) (user.User, error) {
 	}
 	u, ok := m.users[id]
 	if !ok {
-		return user.User{}, gorm.ErrRecordNotFound
+		return user.User{}, user.ErrUserNotFound
 	}
 	return u, nil
 }
@@ -49,7 +49,7 @@ func (m *mockUserRepo) GetByUsername(username string) (user.User, error) {
 			return u, nil
 		}
 	}
-	return user.User{}, gorm.ErrRecordNotFound
+	return user.User{}, user.ErrUserNotFound
 }
 
 func (m *mockUserRepo) GetByEmail(email string) (user.User, error) {
@@ -62,7 +62,7 @@ func (m *mockUserRepo) GetByEmail(email string) (user.User, error) {
 			return u, nil
 		}
 	}
-	return user.User{}, gorm.ErrRecordNotFound
+	return user.User{}, user.ErrUserNotFound
 }
 
 func (m *mockUserRepo) GetAll() []user.User {