[NTG-context] Problem with \vfill in extreme table

17 May 2020

      If I want the words Top and Bottom at the top and bottom of a page then "Top \vfill Bottom" works as expected. If I use the same in an extreme table I get an error and I don't know why.

What's the 'official' way to align top and bottom in an xrow? 

%%%% MWE
\setuppapersize [A4] [A4]
\starttext
\startxtable[width=\textwidth]
  \startxrow[height=150mm]
    \startxcell[align=middle]
      Top
      \vfill
      Bottom
    \stopxcell
  \stopxrow
\stopxtable
\stoptext
%%%%

The error message is:
...
tex error       > tex error on line 4 in file virtual://buffer.x_table_1.2: ! Missing } inserted
<inserted text> 
}
<to be read again> 
\vfill 
l.4       \vfill
Version: This is LuaTeX, Version 1.12.0 (TeX Live 2020) 
--
Bruce Horrocks
Hampshire, UK