Consider the input
\documentclass{elsarticle}%%% V3.1 from CTAN
\usepackage{hyperref}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@misc{MITRE-CWE-ConcurrencyIssues,
author = {{The {MITRE} corporation}},
title = {{CWE} category: concurrency issues},
year = 2017,
month = may,
note={\url{http://cwe.mitre.org/data/definitions/557.html}}
}
\end{filecontents}
\bibliographystyle{elsarticle-num}%%% Version 2.1 from http://mirrors.ctan.org/macros/latex/contrib/elsarticle/elsarticle-num.bst
\begin{document}
\cite{MITRE-CWE-ConcurrencyIssues}
\bibliography{\jobname}
\end{document}
Running the usual pdflatex-bibtex loop on it produces an error message:
You can't pop an empty literal stack for entry MITRE-CWE-ConcurrencyIssues
while executing---line 1499 of file elsarticle-num.bst
ptr=1, stack=
(May 2017)
---the literal stack isn't empty for entry MITRE-CWE-ConcurrencyIssues
while executing---line 1499 of file elsarticle-num.bst
Bibtex does its job but returns error code 2, which prevents further automatic processing. Is there any error in the input, in bibtex or in the .bst file? In the latter case, how to repair elsarticle-num.bst?