Cannot remap because neither has a Unicode value assigned in any of the cmap tables

[mawkler]

I get the following warnings when trying to patch FiraCode:

> pyftfeatfreeze -f 'ss01,ss04,ss05,zero' /usr/share/fonts/FiraCode/FiraCode-Regular.ttf ~/.fonts/FiraCode.ttf
WARNING: [applySubstitutions] Cannot remap 'zero.tosf' -> 'zero.tosf.zero' because neither has a Unicode value assigned in any of the cmap tables.
WARNING: [applySubstitutions] Cannot remap 'dollar_greater.liga' -> 'dollar_greater.liga.ss04' because neither has a Unicode value assigned in any of the cmap tables.
WARNING: [applySubstitutions] Cannot remap 'less_dollar.liga' -> 'less_dollar.liga.ss04' because neither has a Unicode value assigned in any of the cmap tables.
WARNING: [applySubstitutions] Cannot remap 'less_dollar_greater.liga' -> 'less_dollar_greater.liga.ss04' because neither has a Unicode value assigned in any of the cmap tables.

When setting those values in the fontfreeze web GUI https://mutsuntsai.github.io/fontfreeze/ it works. I've also tried throwing on the flags -z -S -S Frozen but I still get the warnings. What am I doing wrong?

I'm using the FiraCode installed from the AUR.