Display error log when a modified template has an error so that it could recovery when the error fixed (#22261) (#22321)
backport #22261
A drawback is the previous generated template has been cached, so you
cannot get error in the UI but only from log
Co-authored-by: KN4CK3R <admin@oldschoolhack.me>
Co-authored-by: delvh <dev.lh@web.de>