PS> msdfgen msdf -font FiraSans-Bold.otf g0
No character specified! Use -font <file.ttf/otf> <character code>. Character code can be a Unicode index (65, 0x41), a character in apostrophes ('A'), or a glyph index prefixed by g (g36, g0x24).
Glyph #0, unlike Unicode Character 'NULL', can be a perfectly valid and even visible character. (Furthermore, in an automated asset pipeline, you will want to build every glyph regardless of visibility.)
The cause seem to be using zero as failure indicator instead of using
std::optional.Glyph #0, unlike
Unicode Character 'NULL', can be a perfectly valid and even visible character. (Furthermore, in an automated asset pipeline, you will want to build every glyph regardless of visibility.)