Initial attempt failed, we need to fix the following issues:
SixLabors/ImageSharp#1302 (comment)

Disabling the two (likely) bugs with [ActiveIssue] might be also fine.

I've been treating tuShorten/tuWiden as a string-ish conversion between UTF16 and UTF 8, so I recommend this.

Here's the code; add it to the end of every tuShorten/tuWiden function.
if (out < (original_out + out_len)) out = 0;