message error in biblatex.4ht with tex4ht, even with no bibliography

Question

I have the following message when I compile a document calling biblatex, whether I run biber or not, in order to create a .bbl. I use Biber 2.3.

My file is % biblatex.4ht (2015-08-05-15:37), generated from tex4ht-4ht.tex

The pdf has no error during the compilation, only the tex4ht complains.

(/texlive/texmf-dist/tex/generic/tex4ht/biblatex.4ht
! Missing = inserted for \ifnum.
<to be read again>
.
l.158 \ifnum\blx:ver:no
                      < 3
?
! Missing number, treated as zero.
<to be read again>
.
l.158 \ifnum\blx:ver:no
                      < 3
?
! Missing = inserted for \ifnum.
<to be read again>
.
l.359 \ifnum\blx:ver:no
                      < 3
?
! Missing number, treated as zero.
<to be read again>
.
l.359 \ifnum\blx:ver:no
                      < 3

the document is simple, since it has nothing in it.

i compile with make4ht -ul hello.tex "fn-in"

I use an extension of tex4ht by @michal.h21,

https://github.com/michal-h21/helpers4ht

But I od not believe it influence anything since I do not activate it here.

\documentclass[oneside,a4paper, 12pt]{article}


\usepackage[backend=biber, language=british]{biblatex}


% \usepackage{alternative4ht}
%  \altusepackage{fontspec}
%  \setmainfont{TeX Gyre Termes}
%%  \newfontfamily\greekfont{Linux Libertine O}
%%  \newfontfamily\russianfont{Linux Libertine O}
%%  \newfontfamily\hindifont{Siddhanta}
%  \altusepackage{polyglossia}
%  \setmainlanguage{french}
%%  \setotherlanguage{czech}
%%  \setotherlanguage{greek}
%%  \setotherlanguage{russian}
%%  \setotherlanguage{hindi} 




\begin{document}

cou

\end{document}

Answer 1

The current version (2015-08-05-15:37) of biblatex.4ht in TeX live contains the line

\ifdefstring{\abx@version}{3.0}{\xdef\blx:ver:no{3}}{\xdef\blx:ver:no{2.9}}

Since you are running version 3.1 or 3.2 of biblatex (and thus not 3.0), you get \blx:ver:no set to 2.9. But then \ifnum has trouble with non-integers, so everything goes pear-shaped.

You can fix the problem by replacing the line above with a simple

\xdef\blx:ver:no{3}