Error in error handling

[stever]

In callbacks, when there is a fatal PHP error, it causes a JS error as well.

	/**
	 * Respond to Prado Callback request exceptions.
	 */
	Exception :
	{
		/**
		 * Server returns 500 exception. Just log it.
		 */
		"on500" : function(request, transport, data)
		{
			var e = request.getHeaderData(Prado.CallbackRequest.ERROR_HEADER);
			Logger.error("Callback Server Error "+e.code, this.formatException(e));
		},

If there was a fatal error, the error header never gets set, so var e=null above, and e.code causes a JS error. Better if it looked like this (or similar):

	/**
	 * Respond to Prado Callback request exceptions.
	 */
	Exception :
	{
		/**
		 * Server returns 500 exception. Just log it.
		 */
		"on500" : function(request, transport, data)
		{
			var e = request.getHeaderData(Prado.CallbackRequest.ERROR_HEADER);
			if (e)
				Logger.error("Callback Server Error "+e.code, this.formatException(e));
			else
				Logger.error("Callback Server Error Unknown",'');
		},