Add error when readBalanced fails to balance at end of Mouth

[dginev]

This was a bit of a shocker in Authorea editing. There were obvious pieces of wrong LaTeX content that never returned an error from latexml, such as:

\textbf{some text here

Importantly, this is being converted in fragment mode, and has no \end{document} in the same mouth to throw a grouping error. This revealed a particular case of unreported errors in LaTeXML:

When a Gullet->readBalanced call does not have a closing brace, the read silently succeeds to slurp all content until the end of the Mouth

This can cause some serious issues if the error is committed early in a large chunk of latex, naturally. So I suggest throwing an informative error, and then proceeding as usual. It is good enough for users to correct their mistake in online editing. Example interface from Authorea:

Feedback welcome on how exactly to structure the error.

[dginev]

To reproduce the error in the master latexml from the command-line, here is a one-liner:

latexmlc --whatsin=fragment --preload=article.cls 'literal:\textbf{example...'

I would clearly expect this to throw an error, such as the one from this PR

[brucemiller]

Thanks; Actually, I have a nagging doubt that there was a reason to leave w/o error, but can't remember why; perhaps the usually-expected error that follows is a clearer one? Anyway, merge and see what happens :>

[dginev]

I was investigating the potential reasons, and the most pertinent bit of logic was the fact some Mouths autoclose and some do not. There is some subtle intention there that I half-understood, but I tested around several conditions and none seemed to print a decent error for this specific case. Maybe it is even subtler!

We'll be informed upon the next arXiv rerun :>

[dginev]

I may have found out why it was there. I am now getting a rather unpleasant error when loading elsarticle.cls, on a vanilla empty-ish input:

gullet->readbalanced ran out of input in an unbalanced state.
 /usr/local/share/perl/5.22.1/LaTeXML/Package/elsart_support.sty.ltxml line 236 Input is empty In 
Core::Gullet[@0x30a84f18] /usr/local/share/perl/5.22.1/LaTeXML/Package/elsart_support.sty.ltxml line 
236 <= Core::Definition::Primitive[\newenvir... <= Core::Stomach[@0x30ace348] <= 
Core::Gullet[@0x30a84f18] <= ..

Hm, need a way to keep the error for the good cases, but kick it out of here.

[dginev]

Basically it's the technique used internally by RawTeX, I'm amazed we don't have any tests that use that and would fail?

$stomach->getGullet->readingFromMouth(LaTeXML::Core::Mouth->new($text), sub {

[dginev]

Well, while I have connected the error to the piece of code using a new Mouth, I haven't yet connected to the exact reason readBalanced would fail on a perfectly balanced input.

[dginev]

Exact RawTeX line with this error is:

RawTeX('\newenvironment{pf}{\begin{@proof}[\proofname]}{\end{@proof}');

[dginev]

One-liner to reproduce:

latexmlc --preamble='literal:\documentclass{elsarticle}' literal:test

[dginev]

Oh my.

After staring here for an unreasonable amount of time... Is there a typo in the RawTeX string? I printed a whole lot of Dumper messages and it now looks as if the ending:

{\end{@proof}

should have an additional ending brace:

{\end{@proof}}

Does this make sense? I can commit that right away.

[dginev]

I have verified this is the issue, will push directly to master (since we're talking 1 character)

[dginev]

Done: a090611

Hope you don't mind my first commit to master @brucemiller ! I think this PR may catch some interesting RawTeX oversights now, more convinced it was correct to add this error message.

[brucemiller]

bravo & welcome ! :>