makebst generated bibtex file - Error: You can't pop an empty literal stack for entry

Question

When I compile the following latex code:

\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[latin9]{inputenc}
\usepackage{babel}
\begin{document}
\cite{Lyklema_Fundamentals_1995_} \bibliographystyle{jjap_bml}
\bibliography{tmp}
\end{document}

With the following .bib file

@book{Lyklema_Fundamentals_1995_,
  address = {Cambridge, Massachusetts},
  title = {the title},
  abstract = {},
  publisher = {a publisher},
  author = {Lyklema, J.},
  month = oct, 
  year = {1995}}

And using this .bst generated using makebst (this script), I get the following error:

You can't pop an empty literal stack for entry Lyklema_Fundamentals_1995_
while executing---line 1171 of file jjap_bml.bst
(There was 1 error message)

But I cannot understand what the problem is. I can 'view the output anyway' and find the reference is formatted incorrectly as:

"J. Lyklema, the title, (a publisher, Cambridge, Massachusetts1995)."

i.e. there is no comma between the 'location' and 'date' field.

I'd be very grateful for any help.

EDIT: This issue has been resolved by simply editing one line of .bst; please see the first comment by Troy.