DOM exception thrown when the network cable is removed

The exception NS_ERROR_DOM_INVALID_EXPRESSION_ERR is being thrown in the web application when the network cable is removed. The web app constantly sends and receives message from the server.

Can anyone tell what could be causing this error 开发者_StackOverflow中文版and how to fix this issue?

---

The web app should be checking the return value of it's AJAX calls before attempting DOM manipulations on the results.