Why do i get errors in external JavaScript but not if i use same code as internal JavaScript

Question

https://code.sololearn.com/Wv2CjtdT250I/?ref=app

Answer 1

https://www.sololearn.com/post/90825/?ref=app

https://code.sololearn.com/WKKkpq0efxai/?ref=app

Answer 2

Ok,corrected,tnx