Refactor: remove questions check from addscalestandarderror

It is not necessary and not the responsibility of this class to check
if no questions are remaining.

classes/teststrategy/preselect_task/addscalestandarderror.php

@@ -71,10 +71,6 @@ public function __construct() {
      *
      */
     public function run(array &$context, callable $next): result {
-        if (count($context['questions']) === 0) {
-                return result::err(status::ERROR_NO_REMAINING_QUESTIONS);
-        }
-
         $cache = cache::make('local_catquiz', 'adaptivequizattempt');
         $context['playedquestionsperscale'] = $this->getplayedquestionsperscale();
         $cachedresponses = $cache->get('userresponses');