They aren't contributing to rendering and making issue for stroking, let's skip them
ourselves as Skia does also https://skia-review.googlesource.com/c/skia/+/268166
They are useful for extracting extents and so which that functionality won't be effected by this change.
This doesn't imply the the design is good or stable just is better
to not fail due to null quad-to callback so as our quad-cubic curves
translation is currently table limited which can be revisited anytime.
Ebrahim Byagowi