Updated solution to charge in center of ring using chemfig?

• Until chemfig v1.55, node arccenter is defined per arced ring.
• In chemfig v1.56 (updated on 13 July 2020), nodes at the center of rings are named cyclecenter<n>. Here <n> is 1, 2, 3, ... which indicates the center of <n>th ring in one \chemfig.
• For source code changes, see diff of chemfig.tex between v1.55 and v1.56 (open and search for arccenter), from TeX Live's SVN repository.
• For official documentation and usage examples about cyclecenter<n>, see manual of chemfig v1.56, section 12.6.

Therefor, with chemfig v1.56, just replace node name arccenter with cyclecenter1.

\documentclass{article}
\usepackage{chemfig}

\begin{document}
\chemfig{**[0,-150,dash pattern=on 2pt off 2pt,
       late options={name=cyclecenter1,label=center:+}]5(-----)}
\end{document}