Error on unwrapping string email and password

User.swift

//
//  User.swift
//  GeneratorPass
//
// Developer: http://riccardopirani.altervista.org
//  Created by riccardo 
//  Copyright © 2016 ViewSoftware. All rights reserved.
// Software House: http://viewsoftware.it

import Foundation

class User{
    
    //URL to our web service
    let URL_SAVE_TEAM = "http://localhost/test/login_mobile.php"
    var email:String?=""
    var password:String?=""
    
    
    func PrintValue(){
        
       // print(username);
        //print(password);
    }
    
    func Login() -> String{
    
        let emailwrap=email!
        let pwdwrap=password!
        
        var ris="";
        //created URL
        guard let requestURL = URL(string: URL_SAVE_TEAM) else { return "no" }
        
        //creating URLRequest
        var request = URLRequest(url: requestURL)
        
        //setting the method to post
        request.httpMethod = "POST"
        
        //getting values from text fields
        
        
        //creating the post parameter by concatenating the keys and values from text field
        let postParameters = "email=\(emailwrap)&password=\(pwdwrap)"
        
        //adding the parameters to request body
        request.httpBody = postParameters.data(using: .utf8)
        
        //creating a task to send the post request
        let session = URLSession.shared
        
        let task = session.dataTask(with: request) {
            data, response, error in
            
            guard error == nil else {
                print("error is \(error!.localizedDescription)")
                return
            }
            
            guard let data = data else {
                print("No data was returned by the request!")
                return
            }
            
            //parsing the response
            do {
                //converting resonse to NSDictionary
                let myJSON =  try JSONSerialization.jsonObject(with: data, options: .allowFragments) as? Dictionary<String, String?>
                
                //parsing the json
                guard let parseJSON = myJSON, let msg = parseJSON["message"] as? String else {
                    print("Error parsing data")
                    return
                }
                
                //printing the response
                print("Responso di ritorno: "+msg)
                
                ris=msg;
                
            } catch {
                print(error)
            }
            
        }
        
        //executing the task
        task.resume()
        
        
        return ris;
    }
    
    
}