fix: improve error message

src/main/java/no/ntnu/idi/stud/savingsapp/exception/user/UserException.java

+package no.ntnu.idi.stud.savingsapp.exception.user;
+
+/**
+ * Exception thrown regarding a user in the system.
+ */
+public final class UserException extends RuntimeException {
+
+  /**
+   * Constructs a UserException with the default message.
+   */
+  public UserException(String string) {
+    super(string);
+  }
+}

src/main/java/no/ntnu/idi/stud/savingsapp/service/impl/UserServiceImpl.java

@@ -9,6 +9,7 @@ import no.ntnu.idi.stud.savingsapp.bank.service.AccountService;
 import no.ntnu.idi.stud.savingsapp.exception.auth.InvalidCredentialsException;
 import no.ntnu.idi.stud.savingsapp.exception.user.EmailAlreadyExistsException;
 import no.ntnu.idi.stud.savingsapp.exception.user.InvalidPasswordResetTokenException;
+import no.ntnu.idi.stud.savingsapp.exception.user.UserException;
 import no.ntnu.idi.stud.savingsapp.exception.user.UserNotFoundException;
 import no.ntnu.idi.stud.savingsapp.model.BankAccountType;
 import no.ntnu.idi.stud.savingsapp.model.user.Feedback;
@@ -225,8 +226,8 @@ public class UserServiceImpl implements UserService {
     try {
       return userRepository.save(user);
     } catch (DataIntegrityViolationException e) {
-      log.error("[UserServiceImpl:update] email already exists: {}", user.getId());
-      throw new EmailAlreadyExistsException();
+      log.error("[UserServiceImpl:update] data integrity violation: {}", e.getMostSpecificCause().getMessage());
+      throw new UserException(e.getMostSpecificCause().getMessage());
     }
   }