“Update” button adds glyphs in Glyph Builder

[arialcrime]

While using the Glyph Builder I recently observed the following behaviour which made me a bit suspicious:

I open a new, empty font and save it, then start GlyphConstruction’s Glyph Builder (version 0.8.4), and type testglyph = test + glyph as a recipe. When I then hit the “Update” button, I get the following callback in the Output window:

Failed to read glyph: 'test': 'test not in layer'
'test'
Failed to read glyph: 'glyph': 'glyph not in layer'
'glyph'

It also causes the font to become “dirty”, and when I save it empty glyphs called “test” and “glyph” show up in the glyphs folder, contents.plist, and the lib’s public.glyphOrder.

My expectation after clicking “Update” would have been that I would only get a trackback about the missing glyphs, not that there would be new ones added.

Am I misunderstanding something here or simply doing it wrong? Thanks for your help!

[arialcrime]

Do you know what is happening here @typemytype?