Failed custom build using Docker

[unennhexium]

Command

❯ docker run --rm -v "${PWD}":/opt tonsky/firacode:latest ./script/build.sh --family-name "Fira Code Custom" --weights "Regular,Medium,SemiBold,Bold"

Output

Creating font with family name: Fira Code Custom
Generated glyphs file: Fira Code Custom.glyphs
==============

  [i] Creating distr/otf/Fira Code Custom/FiraCode-Regular.otf

INFO:fontmake.font_project:Building master UFOs and designspace from Glyphs source
INFO:glyphsLib.classes:Parsing "/tmp/tmp.kpcR1dq1Mk.glyphs" file into <GSFont>
fontmake: Error: In '../tmp/tmp.kpcR1dq1Mk.glyphs': Loading Glyphs file failed: 'str' object has no attribute '_parent'

[BigfootN]

I'm having the exact same problem