SyntaxError: Unexpected token < in JSON at position 0 in Ionic2 App - php

Question

I register the data to the database.Then I want to list the data but I get an error(SyntaxError: Unexpected token < in JSON at position 0).I do not understand where I'm making mistakes.
list.html
<ion-header>
<ion-navbar>
<ion-title>list</ion-title>
</ion-navbar>
</ion-header>
<ion-content padding>
<ion-list>
<ion-item *ngFor="let isim of dataisim">{{isim}}</ion-item>
</ion-list>
</ion-content>
list.ts
import { Component } from '#angular/core';
import { IonicPage, NavController, NavParams } from 'ionic-angular';
import {ServiceProvider} from "../../providers/datamember";
import { Http, Headers, Response, ResponseOptions } from '#angular/http';
#IonicPage()
#Component({
selector: 'page-list',
templateUrl: 'list.html',
})
export class ListPage {
dataisim : any;
constructor(public navCtrl: NavController, public navParams:
NavParams,public service:ServiceProvider,
public http : Http) {
}
ionViewDidLoad() {
console.log('ionViewDidLoad ListPage');
this.service.getList().subscribe(data =>
this.dataisim = data );
console.log(this.dataisim);
}
}
service.ts
import { Injectable } from '#angular/core';
import { Http, Headers, Response, ResponseOptions } from '#angular/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/map';
import { Storage } from '#ionic/storage';
#Injectable()
export class ServiceProvider {
public local : Storage;
mydata : any;
api : string = 'http://localhost:8080/ionic2_kaydet.php';
api2 : string = 'http://localhost:8080/kaydet3.php';
url : string = "http://localhost:8080/listele.php";
constructor(public http: Http) {
}
postLogin(data){
console.log("api data:" + data);
let headers = new Headers({ 'Content-Type' : 'application/x-www-form-
urlencoded' });
return this.http.post(this.api, data, {
headers:headers,
method:"POST",
}).map(
(res:Response) => {return res.json();}
);
}
getList() {
let headers = new Headers({ 'Content-Type' : 'application/x-www-form-
urlencoded' });
return this.http.get(this.url, {
headers:headers,
method:"GET",
}).map(
(res:Response) => {return res.json();}
)
}
}
listele.php
<?php
header("Access-Control-Allow-Origin: *");
$conn = new mysqli("localhost", "root", "", "ionic2");
$data= array();
$select = "select * from user2";
$qr = $conn->query($select);
while($row = $qr->fetch_assoc()){
$data[]=$row;
}
print json_encode($data);
?>