[Tex/LaTex] How to Debug “Too Deeply Nested” error

nesting

I see that numerous people have asked a similar question. At the risk of annoying you LaTeX experts, the problem is, as I have expressed before, that LaTeX is a truly awful language. Having said that, someone who is a reasonably competent programmer in Java/C++/Perl/Python etc ought to be able to debug a program that stops working.

Currently, the only way I have to debug a failure is to either quickly undo if I have luckily only written a few lines, or to comment out blocks of code until I identify the region where the problem is. This is completely unacceptable. If that's the only way, then the language is at fault. I am looking for any help in how to find an error WITHOUT having to edit hundreds of lines.

I compile my code and the console given an error on line 709:

\materials
\begin{itemize}
\item photoresistor (3k)
\item resistor (2.2\kohm)
\end{itemize}

The \materials command is defined as:

\newcommand{\materials}{{\bf Materials:}}

The item with photoresistor is the one giving the error. Presumably this means that there are unclosed \begin{itemize} commands before?

Q1: What are the possible causes of this error. Could there be any OTHER unclosed entity causing it? What about \begin{enumerate} ?

Q2: How can I find it, aside from searching every \begin{itemize} and manually looking for the matching \end{itemize}

Q3: Is there any code I can write to assert that everything must be closed, or to display the location of any open \begin? This would go a long way towards solving this problem!!!

Best Answer

If you suspect that you have unclosed groups then let TeX get to the end, or if other errors stop tex or obscure the problem, add \stop at a point that you want to test, and look at the terminal output or log.

So for example

\documentclass{article}

\begin{document}

aaa

\begin{itemize}
\item xxx
\item xxx
\end{itemize}

bbb

\begin{itemize}
\item xxx
\item xxx
%oops\end{itemize}

bbbb

\begin{itemize}
\item xxx
\item xxx
\end{itemize}



\stop



more stuff here

other \ERROR we are not concerned about

If you run the above, TeX stops at the \stop and the terminal output shows

(\end occurred inside a group at level 1)

### semi simple group (level 1) entered at line 14 (\begingroup)

so the level 1 means that you have exactly one extra open group and the second line tells you that it's a semi simple group, which means it is started with \begingroup not { so in latex most likely started by \begin

then it tells you it started on line 14 which is exactly the

\begin{itemize}

line for the list with the missing \end.

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