Resolve index issue in php laravel [duplicate]

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• “Notice: Undefined variable”, “Notice: Undefined index”, and “Notice: Undefined offset” using PHP 27 answers

I'm trying to display download links(pdf) on my page but I'm getting an index error

Undefined offset: 6 (View: C:\xampp\htdocs\bluepenlabs\fta\app\Modules\Fta\views\frontoffice\Fta\voir-docs.blade.php)

This is my controller :

 public function docs(){
        $docs = Document::all();
        return view("Fta::frontoffice.Fta.voir-docs",compact('docs'));
 }

this is the view

 <?php
       if(file_exists(public_path('frontoffice/fichiers/docs'))){
         $files = File::allFiles(public_path('/frontoffice/fichiers/docs/'));
       }
       if(!empty($docs)){
               foreach ($docs as $doc){
                     //$fichier = explode("/", $file);
                     $fichier = explode("-", $doc['file']);
                    $ext = explode(".", $fichier[6]);

  ?>
        <span style="font-size: x-large;color: royalblue;"></span>
         <br><br>
         <p style="color: black">{!!  $doc->description !!}</p>
         <a href="/frontoffice/fichiers/docs//" download style="font-size: x-large"></a>

          @if($ext[1]== "pdf")
                <div class="box"><iframe src="/frontoffice/fichiers/docs//" width = "300px" height = "300px"></iframe></div>
           @endif  
           <br>   
           <medium> Crée le :  <br>Modifier le : </medium>
            <hr>
             <?php }
                   }
                  ?>

I tried to dd($fichier) it gives me this :

via Chebli Mohamed