prevent php-warnings in adminssion, fixes #4767

Closes #4767

Merge request studip/studip!3553

app/controllers/course/admission.php

@@ -317,6 +317,7 @@ class Course_AdmissionController extends AuthenticatedController
         } else {
             $this->request = $request;
             $this->button_yes = 'change_admission_turnout_yes';
+            $this->button_no = 'change_admission_turnout_no';
             PageLayout::postInfo($question);
             $this->render_template('course/admission/_change_admission.php');
         }
@@ -405,6 +406,7 @@ class Course_AdmissionController extends AuthenticatedController
         } else {
             $this->request = ['change_course_set_unassign' => 1];
             $this->button_yes = 'change_course_set_unassign_yes';
+            $this->button_no = 'change_course_set_unassign_no';
             PageLayout::postInfo($question);
             $this->render_template('course/admission/_change_admission.php');
         }

app/views/course/admission/_change_admission.php

+<?php
+/**
+ * @var Course_AdmissionController $controller
+ * @var array $request
+ * @var string $button_yes
+ * @var string $button_no
+ */
+?>
+
 <? foreach(PageLayout::getMessages() as $pm) : ?>
     <?= $pm ?>
 <? endforeach; ?>
@@ -7,7 +16,7 @@
     <?= addHiddenFields($k, $v) ?>
 <? endforeach ?>
 <footer data-dialog-button>
-    <?= Studip\Button::create(_("Ja"), $button_yes, ['data-dialog' => ''])?>
-    <?= Studip\Button::create(_("Nein"), $button_no, ['data-dialog' => ''])?>
+    <?= Studip\Button::create(_('Ja'), $button_yes, ['data-dialog' => ''])?>
+    <?= Studip\Button::create(_('Nein'), $button_no, ['data-dialog' => ''])?>
 </footer>
 </form>