有时获取数据并且有时会在Angularjs中使用Laravel 5.7给出一个无效的json错误？ 寻找答案

Question

I am working in laravel 5.7 along with angularjs. I receive the data but sometimes it gives me data and sometime it gives me an error which is data is not valid json form, parse {} error. Below is my angularjs code

$http({
      method: "GET",
      url : "get-portlanding" //Laravel route
}).then(function(response){
      $scope.portlanding= response.data;
});

Below is laravel controller code.

public function GetPortLanding(){

     $result = Portlanding::all();
     return response->json($result);
}

Below is error picture What am i doing wrong can anyone help me out of this headache. Thanks