prevent php-warnings in questionnaire and my_courses, fixes #4665

Closes #4665

Merge request studip/studip!3476

app/controllers/file.php

@@ -1473,7 +1473,7 @@ class FileController extends AuthenticatedController
                 }
                 $payload = [
                     'html'     => FilesystemVueDataManager::getFileVueData($newfile, $this->current_folder),
-                    'redirect' => $redirects[0],
+                    'redirect' => $redirects[0] ?? '',
                     'url'      => $this->generateFilesUrl($this->current_folder, $newfile),
                 ];
 

app/controllers/my_courses.php

@@ -475,6 +475,7 @@ class MyCoursesController extends AuthenticatedController
                     ));
                 }
             } else {
+                $prio_delete = false;
                 // LOGGING
                 StudipLog::log('SEM_USER_DEL', $course_id, $GLOBALS['user']->id, 'Hat sich selbst aus der Warteliste ausgetragen');
                 if ($course->isAdmissionEnabled()) {

app/views/questionnaire/question_types/vote/vote_evaluation.php

@@ -83,7 +83,12 @@ rsort($ordered_results);
 
 <table class="default nohover">
     <tbody>
-        <? $countAnswers = $vote->questionnaire->countAnswers() ?>
+        <?php
+            $countAnswers = 0;
+            if ($vote->questionnaire) {
+                $countAnswers = $vote->questionnaire->countAnswers();
+            }
+        ?>
         <? foreach ($options as $key => $answer) : ?>
         <tr>
             <? $percentage = ($countAnswers && isset($results[$key])) ? round((int) $results[$key] / $countAnswers * 100) : 0 ?>