Correction : change ->server to ->server() (use a method instead an object field)

app/Http/Controllers/MarkController.php

@@ -290,7 +290,7 @@ class MarkController extends Controller
     {
         $ev = $this->server()->findEvidenceById($id);
         $query = $ev->requests[$data_id];
-        $data = $this->server->findDataByQuery($query);
+        $data = $this->server()->findDataByQuery($query);
 
         return view('app.data', [
             "evidence" => $ev,