php - Array in foreachloop returns additional null value

I have a problem in php.

So, i have a
json data which i will decode and put in object
Then, i will use foreach
function for gettings the parameters.
I'll be putting this to a array so i can
call it outside of the loop.
However,when i'm displaying the results it
returns a additional null value like
this:

[{"mobile":"639179512744"},{"mobile":"639054971214"},
            {"mobile":"639394297841"},{"mobile":"639296378818"},{"mobile":"639265161309"},{"mobile":null}]

Where
the last record should not be included. I only have 5 records of
mobile.

Here is my
code:

$data =
            file_get_contents("php://input");
$data =
            (object)json_decode($data);
$model = $data->data;
$model =
            json_encode($model);
$model = json_decode($model);
$model =
            (object)$model;
foreach($model AS $row){
 $mobile =
            $row->mobile_number;

 $array[] = array(

            'mobile'=>$mobile
 );

}

echo
            json_encode($array);

And
here is the
data:

{"action":"upload","data":[{"mobile_number":"639179512744","sentdt":"2017-
            02-07 00:21:57","imsi":"","remarks":"ACTIVE"},
            {"mobile_number":"639054971214","sentdt":"2017-02-07
            00:21:57","imsi":"","remarks":"ACTIVE"},
            {"mobile_number":"639394297841","sentdt":"2017-02-07
            00:21:57","imsi":"","remarks":"Absent Subscriber - No International Mobile Subscriber
            Identity"},{"mobile_number":"639296378818","sentdt":"2017-02-07
            00:21:58","imsi":"","remarks":"Absent Subscriber - No International Mobile Subscriber
            Identity"},{"mobile_number":"639265161309","sentdt":"2017-02-07
            00:21:58","imsi":"","remarks":"ACTIVE"},{}]}

Someone
can help?I want to get rid of the additional null
value
Thanks