\peek_analysis_map_inline:n does not work in tabular environment

[jlaurens]

The effect of the \TEST command is to gobble the next token.
Of course, a real life use would not break the analysis so early.

\documentclass{minimal}
\begin{document}
\ExplSyntaxOn
\def \TEST {
  \peek_analysis_map_inline:n {
    \peek_analysis_map_break:
  }
}
\ExplSyntaxOff
\TEST XYZ
\begin{tabular}{c}
\TEST XYZ
\end{tabular}
\end{document}

Things unexpectedly break on the second \TEST call with error

! Argument of \__tl_tmp:w has an extra }.
<inserted text> 
\par 
l.12 \TEST X
          YZ
? 

[user202729]

As a workaround:

\protected\def \TEST {
  \group_align_safe_begin:
  \peek_analysis_map_inline:n {
    \peek_analysis_map_break:n {\group_align_safe_end:}
  }
}

I didn't analyze whether peek_analysis can do that on its own.

[PhelypeOleinik]

The fix, I think, is in the same line as user202829's. Just adding \group_align_safe_begin/end:

\ExplSyntaxOn
\cs_gset_protected:Npn \peek_analysis_map_inline:n #1
  {
    \group_align_safe_begin: % <-- added
    \int_gincr:N \g__kernel_prg_map_int
    \cs_set_protected:cpn
      { __tl_analysis_map_ \int_use:N \g__kernel_prg_map_int :nnN }
      ##1##2##3
      {
        \group_end:
        #1
        \__tl_peek_analysis_loop:NNn
          \prg_break_point:Nn \peek_analysis_map_break: { \group_align_safe_end: } % <-- added
      }
    \__tl_peek_analysis_loop:NNn ? ? ?
  }
\ExplSyntaxOff