Error in mekkablue script "Variable font test html"

This script only works with the axis name “Weight” for me. All other names produce the following error:‘tag’

Traceback (most recent call last):
  File "Variable Font Test", line 1200
    variableFontInfo = otVarInfoForFont(thisFont)
  File "Variable Font Test", line 1140, in otVarInfoForFont
    otVarSliders = allOTVarSliders(thisFont)
  File "Variable Font Test", line 434, in allOTVarSliders
    tag = axisDict[axis]["tag"]
KeyError: 'tag'

Any hints?

Glyphs 3.1.2 (3151)