Re^4: Can't use an undefined value as a HASH reference

The build_subtree subroutine has a sanity test line as follows

  if ($line !~ /^\(.*\)\s*$/) {
    print "here: $line\n";
    return undef;
  }
[download]

And input $line has "1 , 4885".

Comment on Re^4: Can't use an undefined value as a HASH reference Select or Download Code