There are three slugs in every header or footer on Wikisource VisualEditor, and the latter two of them don't work (cause an exception when clicked).
Uncaught TypeError: Cannot read property 'getModel' of undefined at Object.ve.ce.getOffsetOfSlug (load.php?debug=false&lang=pl&modules=ext.CodeMirror.lib|ext.visualEditor.core&skin=vector&version=1eaib6o:593) at VeCeSurface.ve.ce.Surface.createSlug (load.php?debug=false&lang=pl&modules=ext.CodeMirror.lib|ext.visualEditor.core&skin=vector&version=1eaib6o:712) at VeCeMwPagesSectionNode.ve.ce.BranchNode.onSlugClick (load.php?debug=false&lang=pl&modules=ext.CodeMirror.lib|ext.visualEditor.core&skin=vector&version=1eaib6o:624) at NoFocusButtonWidget.oo.EventEmitter.emit (<anonymous>:246:486) at NoFocusButtonWidget.OO.ui.mixin.ButtonElement.onClick (load.php?debug=false&lang=pl&modules=oojs-ui-core&skin=vector&version=1tuzbg3:25) at HTMLAnchorElement.dispatch (load.php?debug=false&lang=pl&modules=jquery%2Cmediawiki|mediawiki.legacy.wikibits&only=scripts&skin=vector&version=1j8y1b9:69) at HTMLAnchorElement.elemData.handle (load.php?debug=false&lang=pl&modules=jquery%2Cmediawiki|mediawiki.legacy.wikibits&only=scripts&skin=vector&version=1j8y1b9:66)