Выдаёт ошибку при вводе имени пользователя

package hello;
 
import org.hibernate.validator.constraints.pl.REGON;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
 
 
import hello.User;
import hello.UserRepository;
 
import javax.jws.soap.SOAPBinding;
import java.util.Map;
 
@Controller    // This means that this class is a Controller
public class MainController {
    @Autowired // This means to get the bean called userRepository
    private UserRepository userRepository;
 
    @GetMapping
    public String main(Map<String, Object> model) {
        Iterable<User> users = userRepository.findAll();
 
        model.put("users", users);
 
        return "main";
    }
 
    @PostMapping
    public String add(@RequestParam String name,@RequestParam String email, Map<String, Object> model) {
        User user = new User(name, email);
 
        userRepository.save(user);
 
        Iterable<User> users = userRepository.findAll();
 
        model.put("users", users);
 
        return "main";
 
    }
 
}