any one know what exit code 256 from tex4ht is supposed to mean? I am getting this error tex4ht.c (2012-07-25-19:36 kpathsea) tex4ht -cunihtf -utf8 KERNEL (/usr/local/texlive/2015/texmf-dist/tex4ht/base/unix/tex4ht.env) --- error --- Improper dvi file Make4ht: Fatal error. Command tex4ht returned exit code 256