Cannot compile `tabular`

[nvmnghia]

This is a sample Overleaf project, which runs fine with LuaTeX 2020.

However, with my latest package, it does not:

• The subfile chapters/chapter 3/test.tex compiles fine

• The main document Lectures.tex does not: it complains that

  Missing control sequence inserted.
  <inserted text>
  \inaccessible
      \end{tabular}
  
  Missing control sequence inserted.
  <inserted text>
  \inaccessible
      \end{tabular}
  
  Missing control sequence inserted.
  <inserted text>
  \inaccessible
      \end{tabular}
  
  Incomplete \ifx; all text was ignored after line 19.
  <inserted text>
  \fi
      \end{tabular}
  
  Missing \endgroup inserted.
  <inserted text>
  \endgroup
      \end{tabular}

  All those complaints are for line 19, which is the line \end{tabular}.

The fact that the subfile compiles but the main file does not makes me think that subfiles has a bug. But it could also be a LaTeX bug (I do update --all daily, even when the test is coming :D).

This is the MWE, in case I edit the Overleaf later:

• preamble.sty

  \ProvidesPackage{preamble}
  
  \usepackage{siunitx}
  \sisetup{
      output-decimal-marker = {,},
      per-mode = symbol,    % m/s instead of default ms^-1
  }
  
  \usepackage{float}
  
  \usepackage{booktabs}
  \usepackage{tabularx}
  
  \usepackage{subfiles} % Best loaded last in the preamble

• Lectures.tex: main file

  \documentclass{book}
  
  \usepackage{preamble}
  
  \begin{document}
  
  \subfile{chapters/chapter 3/test}
  
  \end{document}

• chapters/chapter 3/test.tex: subfile

  \documentclass[../../Lectures]{subfiles}
  
  \begin{document}
  
  \begin{table}[H]
      \centering
      \begin{tabular}{ *{4}{ S[table-format=2.3] } }
          \toprule
          \(x_1\)  &  \(x_2\)  &  \(x_3\)  &  \(x_4\)  \\
          \midrule
           89.062  &   88.281  &   63.281  &   62.891  \\
           87.891  &   87.695  &   62.695  &   62.598  \\
           87.598  &   87.549  &   62.549  &   62.524  \\
           87.524  &   87.512  &   62.512  &   62.506  \\
           87.506  &   87.503  &   62.503  &   62.502  \\
          \bottomrule
      \end{tabular}
  \end{table}
  
  \end{document}

[gsalzer]

Thanks for reporting the bug! I fixed the incompatibility between tabular and subfiles 2.1 in the new release v2.2, currently only available in the main directory of the github repository.