9.23.3 Can you answer these questions?

9.23.3.1 "Something's wrong--perhaps a missing \item": possible MikTeX or package error

https://tex.stackexchange.com/landing/r/digest?cta=question&id=681513

I have set up a latex preamble that generates my custom theorem boxes for definitions, theorems, lemmas etc. I copied pasted it from some guy from here and modified it slightly, and it has been ... 
[errors] [miktex] [tcolorbox]
 

asked by the_dude https://tex.stackexchange.com/landing/r/digest?cta=user&id=227188 Score of 1

9.23.3.2 How can I comment out certain lines in a tabular or longtable?

https://tex.stackexchange.com/landing/r/digest?cta=question&id=681750

I would like to comment out all the content for "version B" in both tables. Is this possible with the usual comment-environments provided by the comment-package? 
MWE 
\documentclass[ 
parskip=... 
[tables] [longtable] [comments]
                                                                                  

                                                                                  
 

asked by henry https://tex.stackexchange.com/landing/r/digest?cta=user&id=25683 Score of 1

9.23.3.3 Highlight underfull boxes

https://tex.stackexchange.com/landing/r/digest?cta=question&id=681566

Overfull \hboxes can be highlighted/marked in the output document by enabling draft=true or overfullrule=true in the \documentclass settings. 
Furthermore, slightly overfull or underfull horizontal ... 
[boxes] [microtype] [draft] [overfull] [underfull]
 

asked by albert https://tex.stackexchange.com/landing/r/digest?cta=user&id=61513 Score of 1