I am while using anytime.js datepicker library of the WordPress wordpress plugin which was custom-produced for me. I only say that because I am not the initial developer and I am afraid to tear the library and change it just in case this means changing plenty of calls to functions which are only at that library.

You can observe that library here: http://www.ama3.com/anytime/

Regrettably, the library is breaking some key benefits from the WordPress after sales by version 3.3. I've confirmed that crippling the library completely fixes the issue.

Google Chrome's console throws the next error:

Uncaught TypeError: Cannot read property 'left' of null
AnyTime.picker.__pickers.(anonymous function).posanytime.js:3032
AnyTime.picker.__pickers.(anonymous function).initializeanytime.js:1858
f.event.dispatchload-scripts.php:3
f.event.add.h.handle.iload-scripts.php:3
f.event.triggerload-scripts.php:3
f.fn.extend.triggerHandlerload-scripts.php:3
(anonymous function)load-scripts.php:3
f.Callbacks.nload-scripts.php:2
f.Callbacks.o.fireWithload-scripts.php:2
e.extend.readyload-scripts.php:2
c.addEventListener.B

within the following lines (3027 - 3039) of anytime.js line 3032 var left = off.left may be the problem type of code based on the console:

        if ( this.pop )
        {
          var off = this.inp.offset();
          var bodyWidth = $(document.body).outerWidth(true);
          var pickerWidth = this.div.outerWidth(true);
          var left = off.left;
          if ( left + pickerWidth > bodyWidth - 20 )
            left = bodyWidth - ( pickerWidth + 20 );
          var top = off.top - this.div.outerHeight(true);
          if ( top < 0 )
            top = off.top + this.inp.outerHeight(true);
          this.div.css( { top: String(top)+'px', left: String(left<0?0:left)+'px' } );
        }

Does anybody have recommendations for how you can debug this?

However , the page is attempting to produce pickers for fields that don't exist. The reason for the issue is not within anytime.js, but is rather within the inline script (particularly, edit.php lines 54 and 55 reported by the browser).

It seems the same picker-creating code has been known as for every page, if the date fields can be found or otherwise. The page shouldn't try to produce a picker for any area that doesn't exist!