Processing a table of contents with the latest standalone (ConTeXt  ver:
2019.01.28 16:58 MKIV beta  fmt: 2019.2.3) fails with the following message:

luatex warning  > hpack filter: error:
...eXt/tex/texmf-context/tex/context/base/mkiv/typo-dua.lua:422: attempt to
compare number with nil


tex error       > tex error on line 18 in file c_Contents.tex: ?



\strc_itemgroups_make_symbol_box ...mbol \fi \fi }

                                                  \let
\strc_itemgroups_extr...

\strc_itemgroups_insert_item ...s_make_symbol_box


\strc_itemgroups_make_dest...

\strc_itemgroups_start_item ...groups_insert_item

                                                  \dostoptagged
\ifcondition...

<to be read again>

\dotagsetitem

\sym ..._symbol \startitemgroupitem \dotagsetitem

                                                  \s!symbol

l.18 \sym{0.}

            Prolegomena to the Study of Hellenistic Astronomy

This worked with the previous standalone.

Alan