$wikipage.offset() is undefined wiki.js:63 from non-existent wiki page

[Jun Omae]

Javascript console says when visiting https://trac.edgewall.org/demo-1.4/wiki/NotFound:

18:44:50.803 TypeError: $wikipage.offset() is undefined wiki.js:63:37
    centerLargeElements https://trac.edgewall.org/demo-1.4/chrome/common/js/wiki.js:63
    wikiColumn https://trac.edgewall.org/demo-1.4/chrome/common/js/wiki.js:68
    <anonymous> https://trac.edgewall.org/demo-1.4/wiki/NotFound:70
    jQuery 4
        i
        fireWith
        ready
        K

Patch:

trac/htdocs/js/wiki.js

@@ -4 +4 @@
   // within its container ($content).
 
   window.wikiColumn = function($wikipage) {
+    if ($wikipage.length === 0)
+      return;
     var $content = $("#content");
     $("<span id='trac-wiki-expander'></span>").on("click", function () {
       $content.toggleClass('narrow');