Strange, possibly hardcoded definition behaviour for non-breaking space

The bug

U+00A0 (non-breaking space) is not defined at all in the default resource pack. Despite this, it still functions correctly to my knowledge, and is distinct from the regular space.

A resource pack that replaces both the space and non-breaking space is attached to this ticket. Use this command to display both:

/tellraw @p {"text": "\u0020\u00a0"}

Expected results

As the non-breaking space is a space-type character, it would be defined in assets/minecraft/font/include/space.json, just like the other characters.

Actual results

For some reason, it is not.