Getting internal server error , when try to fetch data from table using laravel or PHP

I am trying to execute simple CRUD operation using laravel. but it gives an error code 500 , when I try to fetch data from table either by laravel framework as well as with plain PHP.

Here is my controller class.

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use App\BookModel;

class AdminController extends Controller
{
    function getItems()
    {
        $conn = new mysqli('****', '****', '****', '****');
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

$sql = "SELECT * FROM book";
$result = $conn->query($sql);
       // $data = DB::select('select * from book');
        //$data = BookModel::all();
        return $result;
    }
}

My js code , which makes call to controller.

myObject1 = new Vue({
  el: '#Admin',
  data: {
      test:'hey',
      books:[],
      newBook : {bookName:'',autherName:''},

  },
  methods:{
      getBooks : function(){

          _this=this;
          axios.get('getAllBooks').then(function (Response){
              _this.books=Response.data;
          })
      }
  },
  created:function(){
    this.getBooks();
}
})

Error:

spread.js:25 GET http://localhost/lara-vue-login/public/main/getAllBooks 500 (Internal Server Error)
(anonymous) @ spread.js:25
e.exports @ spread.js:25
e.exports @ spread.js:25
Promise.then (async)
r.request @ spread.js:25
r.<computed> @ spread.js:25
(anonymous) @ axios.min.js:477
getBooks @ admin.js:13
(anonymous) @ vue.min.js:6
created @ admin.js:19
t._callHook @ vue.min.js:6
Tt.t._init @ vue.min.js:6
di @ vue.min.js:7
(anonymous) @ admin.js:1


spread.js:25 Uncaught (in promise) Error: Request failed with status code 500
    at e.exports (spread.js:25)
    at e.exports (spread.js:25)
    at XMLHttpRequest.d.onreadystatechange (spread.js:25)

axiom , which is been used. ---> "https://unpkg.com/axios/dist/axios.min.js"

via Chebli Mohamed