SVG export in Observable: error on opening the file

[ericemc3]

Don't know wether it is an Observable or Vega-Lite issue:

I go to https://observablehq.com/@vega/vega-lite-pyramid-pie?collection=@vega/vega-lite-api

I change the render option to svg:
.render({renderer:'svg'});

then try and export via the download SVG item in the Observable cell menu.
When i open the file (in a browser like Chrome or Edge) i get:

This page contains the following errors:
error on line 1 at column 226: Attribute xmlns redefined
Below is a rendering of the page up to the first error.

And indeed, this appears repeated in the svg root node:
xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"

[ericemc3]

It appears that this is probably an Observable issue, so i am noticing their team.

[ericemc3]

Having spoken with the Observable team, it appears that:
it looks like Vega uses setAttribute() to set xmlns attributes, while Observable uses setAttributeNS() in its conversion code,
so in the end these attributes pile up.

I don't know which encoding process is the most academic,
it would just be great if both parties were to agree on the same, considering the great complementarity between both worlds!