fixes #3544

Closes #3544

Merge request studip/studip!2433

app/controllers/course/details.php

@@ -111,7 +111,7 @@ class Course_DetailsController extends AuthenticatedController
                         return false;
                     }
                     $modul_start = Semester::find($modul->start)->beginn ?: 0;
-                    $modul_end = Semester::find($modul->end)->ende ?: PHP_INT_MAX;
+                    $modul_end = $modul->end ? Semester::find($modul->end)->ende : PHP_INT_MAX;
                     return ($modul_start <= $course_end && $modul_end >= $course_start);
                 });
 

lib/models/ModuleManagementModelTreeItem.php

@@ -57,7 +57,7 @@ abstract class ModuleManagementModelTreeItem extends ModuleManagementModel imple
         $types = $types ?: $path;
         $trails = [];
         $class_name = get_class($this);
-        $next = $path[array_search($class_name, $path) + 1];
+        $next = $path[array_search($class_name, $path) + 1] ?? null;
         $parents = $this->getParents($next);
 
         foreach ($parents as $parent) {