this.getDoc() is null in FF using tinymce

I got the problem that when i load my page i immediatly receive the error : `this.getDoc() is null` The function `getBody()` of `Editor.js` gets called and the document seems to be not available ``` getBody : function() { return this.bodyElement || this.getDoc().body; }, ``` In this case getBody() has been triggered by the destroy() function in a gecko code block. ``` destroy : function(s) { var t = this; // One time is enough if (t.destroyed) return; // We must unbind on Gecko since it would otherwise produce the pesky "attempt to run compile-and-go script on a cleared scope" message if (isGecko) { Event.unbind(t.getDoc()); Event.unbind(t.getWin()); Event.unbind(t.getBody()); // here is the relevant getBody() call } ``` Destroy has been triggered by the function addUnload of tinymce.js ``` o.func.call(o.scope, 1); ``` What can i do to avoid this problem?