pdf-rewriter.raku failing to rewrite PDF 1.5 with /XRef and /ObjStm objects

[dwarring]

If I read and write such a PDF:

$ raku -I . bin/pdf-rewriter.raku t/pdf/samples/pdf-1.5-obstm_and_xref_streams.pdf /tmp/out.pdf
opening t/pdf/samples/pdf-1.5-obstm_and_xref_streams.pdf ...
saving ...
done

Then GS no longer works on it:

gs /tmp/out.pdf 
GPL Ghostscript 9.50 (2019-10-15)
Copyright (C) 2019 Artifex Software, Inc.  All rights reserved.
This software is supplied under the GNU AGPLv3 and comes with NO WARRANTY:
see the file COPYING for details.
   **** Error:  An error occurred while reading an XREF table.
   **** The file has been damaged.  This may have been caused
   **** by a problem while converting or transfering the file.
   **** Ghostscript will attempt to recover the data.
   **** However, the output may be incorrect.
   **** Error:  Trailer dictionary not found.
                Output may be incorrect.
   No pages will be processed (FirstPage > LastPage).

   **** This file had errors that were repaired or ignored.
   **** Please notify the author of the software that produced this
   **** file that it does not conform to Adobe's published PDF
   **** specification.

   **** The rendered output from this file may be incorrect.
GS>

The /Index entry in the /XRef is obviously wrong suspicious, and should probably be sorted anyway : [/Index [ 0 1 12 1 19 1 24 ...]