Error in receiving JSON object from API (watch screen capture)

Hello , i have an issure after i used api to connect my application with ionic

here my ts

addRgister(){
	let body = {
    cin: this.cin ,
		fullname: this.fullname ,
	  mailadress: this.mailadress ,
	  password: this.password,
	  aksi: 'add_Register'
	}

	this.postPvdr.postData(body, 'file_aksi.php') .subscribe((data) => {
var alertpesan = data.msg;
if (data.success){
	console.log ('register successful');
}else {
		console.log ('register failed');
}


	});
}

provider-ts :

addRgister(){
	let body = {
    cin: this.cin ,
		fullname: this.fullname ,
	  mailadress: this.mailadress ,
	  password: this.password,
	  aksi: 'add_Register'
	}

	this.postPvdr.postData(body, 'file_aksi.php') .subscribe((data) => {
var alertpesan = data.msg;
if (data.success){
	console.log ('register successful');
}else {
		console.log ('register failed');
}


	});
}

my files php :
config.php

<?php

  define('DB_HOST','localhost');
  define('DB_USER','root');
  define('DB_PASSWORD', '');
  define('DB_NAME','database-pfe');
  $con = mysqli_connect( DB_HOST, DB_USER, DB_PASSWORD, DB_NAME);

?>

my file file_aksi.php

<?php

header ('Access-Control-Allow-Origin: *');
header ("Access-Control-Allow-Credentials: true ");
header ("Access-Control-Allow-Methods: POST, GET, OPTIONS");
header ("Access-Control-Allow-Headers: Content-Type , Authorisation , X-Requested-With");
header ("Content-Type: application.json; charset=utf-8");

include "config.php";

$postjson= json_decode(file_get_contents('php://input'), true);

if($postjson['aksi']=="add_Register"){

  $password= md5($postjson ['password']);
  $query= mysqli_query($mysqli, "INSERT INTO compte SET
    cin= $postjson ['cin'],
    password= $postjson ['password']),
    nom-prenom= $postjson ['fullname'],
    mailadress= $postjson ['mailadress']



  ");

  if($query) {
    $result = json_encode(array('success' => true));
  }
  else
  {
    $result = json_encode(array('success' => false , msg => 'erreur, svp essayer autre fois'));
    echo $result;  
  }
}

?>