I did not understand why recently HN-referenced "which-key" does not work at emacs 25, but work at emacs 27. ChatGPT parsed the cryptic error message and sugges

I did not understand why recently HN-referenced "which-key" does not work at emacs 25, but work at emacs 27. ChatGPT parsed the cryptic error message and suggested remedy, which was (defun string-empty-p (x) (= (length x) 0)) For us with lower level of comprehension, LLMs are literally brain extensions already.