This is pdfTeX, Version 3.14159265-2.6-1.40.19 (TeX Live 2018) (preloaded format=pdflatex 2018.11.28)  23 JAN 2020 14:45
entering extended mode
 restricted \write18 enabled.
 file:line:error style messages enabled.
 %&-line parsing enabled.
**comandi_did
(./comandi_did
LaTeX2e <2018-04-01> patch level 2
Babel <3.18> and hyphenation patterns for 84 language(s) loaded.
\c@teorema=\count80

./comandi_did:39: LaTeX Error: No counter 'chapter' defined.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                              
                                                  
l.39 \newtheorem{teorema}{Teorema}[chapter]
                                           
? 
./comandi_did:39: Emergency stop.
 ...                                              
                                                  
l.39 \newtheorem{teorema}{Teorema}[chapter]
                                           
Your command was ignored.
Type  I <command> <return>  to replace it with another command,
or  <return>  to continue without it.

 
Here is how much of TeX's memory you used:
 34 strings out of 492649
 411 string characters out of 6129621
 56400 words of memory out of 5000000
 4016 multiletter control sequences out of 15000+600000
 3640 words of font info for 14 fonts, out of 8000000 for 9000
 1141 hyphenation exceptions out of 8191
 8i,0n,14p,74b,14s stack positions out of 5000i,500n,10000p,200000b,80000s
./comandi_did:39:  ==> Fatal error occurred, no output PDF file produced!