If you encounter either of the two issues with your paths, don't worry! These are really easy to fix. You can also read more about these in our Common Errors in Type Design guide here.
Glyph contour does not intersect itself
If you're seeing this error, it means that paths that make up your fonts are overlapping. This can cause issues when the fonts are rendered on customer devices, may produce results that you're not happy with, and can make the file sizes larger!
The simple fix is to make sure there are no overlapping paths in your fonts. You can do this easily for your entire font file by selecting all glyphs and using the "Remove Overlap" command in Glyphs App.
Glyph counters have correct winding directions
When glyph counters have incorrect winding directions, counters which should be white will disappear and become black. Paths need to be oriented counter-clockwise, counters need to be oriented clockwise. Read more about this error here.
You can fix any of these in your fonts by selecting all glyphs and using the "Correct Path Direction" command in Glyphs App.