NPE in file dialog indexer

2017-07-30 12:55:50,188 [searchSpringExecutor-2] ERROR SearchCallable - OLAT::ERROR ^%^ N8-E62 ^%^ org.olat.search.service
>>>stack of 1.cause::java.lang.NullPointerException: null
-> at org.olat.search.service.indexer.repository.course.DialogCourseNodeIndexer.checkAccess(DialogCourseNodeIndexer.java:161)
   at org.olat.search.service.indexer.repository.CourseIndexer.checkAccess(CourseIndexer.java:203)
   at org.olat.search.service.indexer.repository.RepositoryIndexer.checkAccess(RepositoryIndexer.java:238)
   at org.olat.search.service.indexer.AbstractHierarchicalIndexer.checkAccess(AbstractHierarchicalIndexer.java:135)
   at org.olat.search.service.indexer.MainIndexer.checkAccess(MainIndexer.java:62)
   at org.olat.search.service.searcher.SearchResultsImpl.createResultDocument(SearchResultsImpl.java:239)
   at org.olat.search.service.searcher.SearchResultsImpl.initResultList(SearchResultsImpl.java:203)
   at org.olat.search.service.searcher.SearchResultsImpl.