Would anyone know what is the problem of the interaction of amsart and microtype under xelatex -- that does not happen under latex, pdflatex or lualatex?
With the file:
\documentclass{amsart}
\usepackage{microtype}
\begin{document}
\begin{abstract}
This is a test.
\end{abstract}
\end{document}
I get the not so clear message:
(/usr/local/texlive/2017/texmf-dist/tex/latex/microtype/mt-LatinModernRoman.cfg)
! Bad character code (-815).
<to be read again>
h
l.6 \begin{abstract}
amsart
requires the use of\maketitle
.