Title not showing in bibliography due to modification of .bst file

Question

I have modified the eprint entry in the hsiam.bst bibliography style file from arXiv (available here). More specifically, I have substituted the format.eprint function for the following one:

FUNCTION {format.eprint}
{ eprint empty$
    { "" }
    { "available in \href{https://arxiv.org/abs/" eprint * "}{arXiv:" eprint * "}" *}
  if$
}

When I cite the following entry

@Article{testone,
  Title                    = {Sample Title},
  Author                   = {Me Myself},

  Month                    = {August},

  Eprint                   = {2222.2222},
  Url                      = {https://arxiv.org/abs/2222.2222}
}

in an MWE like the following:

\documentclass[paper=a4,fontsize=11pt]{article}
\usepackage[sort&compress,numbers]{natbib}
\usepackage{hyperref}
\usepackage{bibentry}
\bibliographystyle{hsiam}

\begin{document}
\nobibliography{biblio}
\begin{enumerate}
\item \bibentry{testone}
\end{enumerate}
\end{document}

I get the following error when compiling with Bibtex:

This is BibTeX, Version 0.99d (MiKTeX 2.9 64-bit) The top-level auxiliary file: main.aux The style file: hsiam.bst Database file #1: publications.bib Warning--empty journal in testone Warning--empty year in testone ptr=1, stack= {\em Sample Title} ---the literal stack isn't empty for entry testone while executing---line 1053 of file hsiam.bst (There was 1 error message)

My guess is that I am calling eprint twice, but I don't know any other way to get the desired result, which should be like this:

M. Myself, Sample Title, available in arXiv:2222.2222, 2015.

Thank you for your time.

Answer 1

So, the solution I have found is to add a * before the second eprint call, having the following code:

FUNCTION {format.eprint}
{ eprint empty$
    { "" }
    { "available in \href{http://arxiv.org/abs/" eprint * "}{arXiv: " * eprint * "}" *}
  if$
}

When compiling the previous MWE, now the output of BibTeX is

This is BibTeX, Version 0.99d (MiKTeX 2.9 64-bit) The top-level auxiliary file: main.aux The style file: hsiam.bst Database file #1: biblio.bib

No errors at all, as looked for.

Thank you all for your help!