Hello all.

As a user of a perl script with no knowledge of perl, it's a bit tricky trying to locate the exact problem. So here I am seeking wisdom from PerlMonks. Posted below is the code snippet originally from https://github.com/mjpost/dptsg/scripts//annotate_spinal_grammar.pl

while (my $line = <>) {
  chomp $line;
    
  my $tree = build_subtree($line);
  
  walk_postorder($tree,[\&mark_heads,\&annotate]);
  
#####offending line's below#######
  @{$tree->{children}}[0]->{label} =~ s/^\*//; # undo top-level merge
  
  print build_subtree_oneline($tree,1), $/;
}

[download]

I've marked the offending line. Would appreciate being guided through resolving error "Can't use an undefined value as a HASH reference at dptsg/scripts/annotate_spinal_grammar.pl line xx, <> line 1."

Thank you.

In reply to Can't use an undefined value as a HASH reference by Anonymous Monk

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