How to fix invalid JSON response in swift when using get request in Alamofire?

I am creating an app wherein it pulls PatientList from API Server and it will display to a TableView. Upon checking, it returns 200 status code but falls to invalidJSON error. But when I checked in Postman, it returns 200 status code and pulls the records properly. I am quite confuse which part of my codes causes the error since I am new in swift. I am seeking help to solve the issue. Below are my sample codes for your references:

Patient.swift

struct Patient: Codable {    let hospitalNumber: Int    let patientName: String    let totalAmount: Doubleenum CodingKeys: String, CodingKey {    case hospitalNumber = "hospitalNumber"    case patientName = "patientName"    case totalAmount = "totalAmount"   }}

APIService.swift

struct PatientList {    typealias getPatientListTaskCompletion = (_ patientListperPayout: [Patient]?, _ error: NetworkError?) -> Void    static func getPatientList(doctorNumber: Int, periodId: Int, completion: @escaping getPatientListTaskCompletion) {        guard let patientPerPayoutURL = URL(string: "\(Endpoint.Patient.patientPerPayout)?periodId=\(periodId)&doctorNumber=\(doctorNumber)") else {            completion(nil, .invalidURL)            return        }        let sessionManager = Alamofire.SessionManager.default        sessionManager.session.getAllTasks { (tasks) in            tasks.forEach({ $0.cancel() })        }        Alamofire.request(patientPerPayoutURL, method: .get, encoding: JSONEncoding.default).responseJSON { (response) in            guard HelperMethods.reachability(responseResult: response.result) else {                completion(nil, .noNetwork)                return            }            guard let statusCode = response.response?.statusCode else {                completion(nil, .noStatusCode)                return            }            switch(statusCode) {            case 200:                guard let jsonData = response.data else{                    completion(nil, .invalidJSON)                    print(statusCode)                    return                }                let decoder = JSONDecoder()                do {                    let patientListArray = try decoder.decode([Patient].self, from: jsonData)                    let sortedPatientListArray = patientListArray.sorted(by: { $0.patientName < $1.patientName })                    completion(sortedPatientListArray, nil)                }catch{                    completion(nil, .invalidJSON)                    print(statusCode)                }            case 400:                completion(nil, .badRequest)            case 404:                completion(nil, .noRecordFound)            default:                print("UNCAPTURED STATUS CODE FROM getPatientList\nSTATUS CODE: \(statusCode)")                completion(nil, .uncapturedStatusCode)                }            }        }

Controller.swift

var patientList: [Patient]! {    didSet {       performSegue(withIdentifier: patientListIdentifier, sender: self)    }}override func viewDidLoad() {    super.viewDidLoad()    self.latestCreditedAmountTableView.dataSource = self    self.latestCreditedAmountTableView.delegate = self    configureTableViewCell()    showTotalCreditedAmount()     getDoctorPayoutSummary(doctorNumber: doctorNumber)}func getDoctorPayoutSummary(doctorNumber: Int) {  self.payoutSummary = payoutSummaryDetails        self.taxRateVatRateLabel.text = "\(self.payoutSummary.taxRate) / \(self.payoutSummary.vatRate)"        self.getPatientList()        self.latestCreditedAmountTableView.reloadData()        return} func getPatientList() {    APIService.PatientList.getPatientList(doctorNumber: doctorNumber, periodId: currentRemittance.periodId) { (patientListArray, error) in        guard let patientListPerPayout = patientListArray, error == nil else {            if let networkError = error {                switch networkError {                case .noRecordFound:                    let alertController = UIAlertController(title: "No Record Found", message: "You don't have current payment remittance", preferredStyle: .alert)                    alertController.addAction(UIAlertAction(title: "OK", style: .default))                    self.present(alertController, animated: true, completion: nil)                case .noNetwork:                    let alertController = UIAlertController(title: "No Network", message: "\(networkError.rawValue)", preferredStyle: .alert)                    alertController.addAction(UIAlertAction(title: "OK", style: .default))                    self.present(alertController, animated: true, completion: nil)                default:                    let alertController = UIAlertController(title: "Error", message: "There is something went wrong. Please try again", preferredStyle: .alert)                    alertController.addAction(UIAlertAction(title: "OK", style: .default))                    self.present(alertController, animated: true, completion: nil)                }            }            return        }        self.patientList = patientListPerPayout        return    }}

JSON Response

[   {"hospitalNumber": null,"patientName": null,"totalAmount": 31104   },   {"hospitalNumber": "","patientName": "LastName, FirstName","totalAmount": 3439.8   }]