A have an error "Trying to get property of non-object" in Laravel

I have code

$room = Room::all();
$book = DB::table('book_rooms')
    ->whereDate('check_out', '>=', $request->check_in)
    ->whereDate('check_in', '<=', $request->check_out)
    ->where(function($query) {
        $query->where('status', '=', 0)
            ->orWhere('status', '=', 1);
    })
    ->groupBy('room_id')
    ->get();

return view('admin.Bookroom.list', ['book' => $book, 'room' => $room]);

So in file list.blade.php show error 'Trying to get property of non-object' Please help me! Thank all

via SpaceLiar