Internal error

From JSXGraph Wiki

[8bbe9d7791fd7f5327610310] /wiki/index.php?title=List_of_available_commands&diff=6820&oldid=1403 Error: Call to a member function getUser() on null

Backtrace:

from /net/httpd/htdocs/jsxgraph/mediawiki-1.40.1/includes/diff/DifferenceEngine.php(1677)
#0 /net/httpd/htdocs/jsxgraph/mediawiki-1.40.1/includes/diff/DifferenceEngine.php(1204): DifferenceEngine->getMultiNotice()
#1 /net/httpd/htdocs/jsxgraph/mediawiki-1.40.1/includes/diff/DifferenceEngine.php(1159): DifferenceEngine->getDiff()
#2 /net/httpd/htdocs/jsxgraph/mediawiki-1.40.1/includes/diff/DifferenceEngine.php(922): DifferenceEngine->showDiff()
#3 /net/httpd/htdocs/jsxgraph/mediawiki-1.40.1/includes/page/Article.php(952): DifferenceEngine->showDiffPage()
#4 /net/httpd/htdocs/jsxgraph/mediawiki-1.40.1/includes/page/Article.php(486): Article->showDiffPage()
#5 /net/httpd/htdocs/jsxgraph/mediawiki-1.40.1/includes/actions/ViewAction.php(78): Article->view()
#6 /net/httpd/htdocs/jsxgraph/mediawiki-1.40.1/includes/MediaWiki.php(556): ViewAction->show()
#7 /net/httpd/htdocs/jsxgraph/mediawiki-1.40.1/includes/MediaWiki.php(333): MediaWiki->performAction()
#8 /net/httpd/htdocs/jsxgraph/mediawiki-1.40.1/includes/MediaWiki.php(923): MediaWiki->performRequest()
#9 /net/httpd/htdocs/jsxgraph/mediawiki-1.40.1/includes/MediaWiki.php(576): MediaWiki->main()
#10 /net/httpd/htdocs/jsxgraph/mediawiki-1.40.1/index.php(50): MediaWiki->run()
#11 /net/httpd/htdocs/jsxgraph/mediawiki-1.40.1/index.php(46): wfIndexMain()
#12 {main}