SVGs generated with blocklys screenshot functionality are kind of invalid

[BjoernLuig]

Describe the bug
SVGs generated with blocklys screenshot functionality are kind of invalid and can not be processed (properly) by some applications.

To Reproduce
Steps to reproduce the behavior:

1. Go to blockly
2. click on "download screenshot"

Show SVG in ubuntu file explorer

Upload SVG to Canva -> doesnt work

Download such an SVG from a Mattermost Message -> Mattermost crashes

Same issues seem to persist over multiple operating systems (Ubuntu, Windows, Mac). Same Programms (Browsers) seem to work around this problem. SVG files from other sources do not have these problems.

Expected behavior
Blocklys screenshot functionality creates a "valid SVG file.

Additional context
Some users had similar problems with invalid SVGs from other sources.
photopea/photopea#4663

[Thiemann96]

from my personal experience using different svg's editors you sort of have to find the right one as not all editor support all svg files. Alternatively we could offer .png files as an alternative

[Thiemann96]

so i can send blockly generated svg's , maybe its a ubuntu problem, it certainly is a mattermost problem though 🤷

[BjoernLuig]

Mattermost also crashed on my Iphone in this case.
But when testing now, mattermost works on all Plattforms, so i would assume it got fixed and is no problem on our side.

(It still does not work in Canva 😔)