Fix: Handle non-Date objects in DateUtil.clone

[winnyboy5]

The DateUtil.clone function previously relied on date.getTime(), which would throw an error if date was not a valid Date object. This could occur if a string, number, or other unexpected data type was passed to the function.

This commit makes DateUtil.clone more robust by handling non-Date objects. The function now checks if the input date is a string. If so, it attempts to parse the string into a Date object using Date.parse(). This allows the function to handle date strings correctly.

This change prevents runtime errors and improves the reliability of DateUtil.clone when dealing with various input types.