join, trying to get property of non-object, ->first, ->firstorfail, ->get()

I'm quite new to Laravel, sorry if this is a simple question. In panitia controller if I use get() I get: Trying to get property of non-object

If I use firstOrFail I get: Call to undefined method Illuminate\Database\Query\Builder::firstOrFail()

If I use first(), it works, but it will show only the first record

The problems is that this code is fine until I need join table.

PanitiaController

 public function lihat($username)
{   
    $panitia=DB::table('panitia')
    ->join('detail', 'panitia.id_panitia', '=', 'detail.id_panitia')
   ->where('username', '=', $username)
   ->first();
   return view('admin.lihat',compact('panitia'));

}

panitia view

@foreach ($panitias as $panitia)

     <tr>
         <td>{{ $panitia->id_panitia }}</td>
         <td>{{ $panitia->username }}</td>
         <td>{{ $panitia->nama }}</td>




         <td><a href="{{url('/admin/panitia/lihat',$panitia->username)}}" class="btn btn-primary">Detail</a></td>
         <td><a href="{{url('/admin/panitia/edit',$panitia->username)}}" class="btn btn-warning">Edit</a></td>
         <td>

         </td>
     </tr>
 @endforeach

lihat view

<div class="form-group">
        <label for="isbn" class="col-sm-2 control-label">Id Panitia</label>
        <div class="col-sm-10">
            <input type="text" class="form-control" id="id_panitia" placeholder={{ $panitia->id_panitia}} readonly>
        </div>
    </div>
    <div class="form-group">
        <label for="title" class="col-sm-2 control-label">Nama</label>
        <div class="col-sm-10">
            <input type="text" class="form-control" id="username" placeholder={{$panitia->username}} readonly>
        </div>
    </div>
    <div class="form-group">
        <label for="title" class="col-sm-2 control-label">Nama</label>
        <div class="col-sm-10">
            <input type="text" class="form-control" id="nama" placeholder={{$panitia->nama}} readonly>
        </div>
    </div>

via Chebli Mohamed