I just tried opening Gimpshop again and got the same error you are seeing. It looks like I upgraded fontconfig at some point since I originally posted this and the upgrade is what caused the problem. I tried recompiling fontconfig/freetype/expat but still ran into the same problem. If you can run an older version of fontconfig, it should still work. I downgraded to 2.7.3 at it seems to work again. I had the older version still on my system so running 'sudo port activate fontconfig@2.7.3_0+macosx+universal' worked for me. While not the right answer, it could be a temporary workaround.
fontconfig
I just tried opening Gimpshop again and got the same error you are seeing. It looks like I upgraded fontconfig at some point since I originally posted this and the upgrade is what caused the problem. I tried recompiling fontconfig/freetype/expat but still ran into the same problem. If you can run an older version of fontconfig, it should still work. I downgraded to 2.7.3 at it seems to work again. I had the older version still on my system so running 'sudo port activate fontconfig@2.7.3_0+macosx+universal' worked for me. While not the right answer, it could be a temporary workaround.