v157 DATE_FORMAT_DATE_PICKER error, if date format change and update product.

Can I change the 32-line code in admin / includes / languages ​​/ english.php or in my native language?

define ('DATE_FORMAT_DATE_PICKER', 'yy-mm-dd'); // Use only 'dd', 'mm' and 'yy' here in any order

I tried modifying the DATE_FORMAT_DATE_PICKER format to the 'dd-mm-yy' format, but when I updated the product,
Admin dashboard cannot appear.

(This page isn't workinglocalhost is currently unable to handle this request.
HTTP ERROR 500

And the LOG file says:

[30-Jun-2020 01:46:28 Europe / Berlin] Request URI: /toko_zc157/blUrt-CXC-cRisp/index.php?cmd=product&cPath=4&pID=2&action=update_product, IP address: :: 1
-> PHP Fatal error: Uncaught Error: Call to a member function format () on bool in D: \ xampp \ htdocs \ toko_zc157 \ blUrt-CXC-cRisp \ includes \ modules \ update_product.php: 22
Stack trace:
# 0 D: \ xampp \ htdocs \ toko_zc157 \ blUrt-CXC-cRisp \ product.php (33): require ()
# 1 D: \ xampp \ htdocs \ toko_zc157 \ blUrt-CXC-cRisp \ index.php (11): require ('D: \\ xampp \\ htdocs ...')
# 2 {play}
thrown in D: \ xampp \ htdocs \ toko_zc157 \ blUrt-CXC-cRisp \ includes \ modules \ update_product.php on line 22.

thank