Making a synchronous $.ajax request that completes with a server exception, an exception thrown inside the "error" callback cannot be caught by an outer try...catch.

That is because in 1.4.2 the result of the request is handled in an asynchronous manner (by attaching a handler to the xhr.onreadystatechange event, even for synchronous requests) thus making it impossible to catch an exception from the error callback.

A possible fix for this could be modifying this line:

var onreadystatechange = xhr.onreadystatechange = function( isTimeout ) {

into:

var onreadystatechange = function( isTimeout ) {

and after the onreadystatechange code block, this should be added:

if (s.async)

{

xhr.onreadystatechange = onreadystatechange;

}