[Forums] CharacterCount results in js error shown as feedback

We have this structure on our page: Table records, where each record contains some text and the expandable area wrapped in a web block. Clicking a hidden button shows the web block via ajax refresh. And inside of it, there is some amount of controls, including one or two CharacterCount controls.

Steps:
1. Expand the control in one of the rows (so that web block with counts is loaded via Ajax)
2. Ajax-refresh the whole table (in our case there are filters that you can change on page, I think it doesn't matter how it is refreshed)
Result: Error message popping up about "error in client script: Cannot read property 'length' of undefined".

Stack trace as shown in JS console:

As I understand, this happens in the javascript of CharacterCount, here:

functioncallBackKeyUp(){that.currValue=that.maxvalue- $(that.input).val().length;
        $(that.place).html(that.currValue);
    }

If I delete CharacterCount - the error stops happening.
It looks like for some reason the control executes it's function after ajax refresh, but since the web block containing it is missing by default - the target input is not found, and the CharacterCount itself is not there either.
One more thing - this happens only once on page, I mean you can only repeat the error again if refresh the page in browser.

Anybody seen this except me? Is there anything that can be done?