charge won't work with chemfig

While chemfig{...} works when I try to make a molecule, charge won’t do anything.

documentclass[11pt]{scrartcl}
usepackage{multicol}
usepackage{chemfig}


title{ }

begin{document}

maketitle

tableofcontents


chemfig{charge{0=:,90=:,270=:}{O}-[:0]C-[:0]charge{90=:,180=:,270=:}{O}}

chemfig{charge{0=:,90=:,270=:}{O}}

chemfig{charge{90=.}{N}H_3}

charge{0=:,90=:,270=:}{O}

end{document}

gives
https://www.overleaf.com/read/rrfbvdfrrrrg.

Even if I use nothing but the package chemfig, it still won’t work: https://www.overleaf.com/read/cqyntshmwrmd

This is really confusing, the error message says "undefined control sequence" when charge should be defined.