function tryCatch(fnFormatter, sInput) {
		return function () {
			try {
				return fnFormatter.apply(this, arguments);
			} catch (ex) {
				Log.warning(String(ex), sInput, sExpressionParser);
			}
		};
	}
Returns a function which wraps the given formatter function into a try/catch block.
In case of an error it is caught, a warning containing the given original input is issued,
and <code>undefined</code> is returned instead.

@param {function} fnFormatter - any (formatter) function
@param {string} sInput - the expression string (used when logging errors)
@returns {function} - the wrapped function