Image.core.outline will no longer raise an AttributeError by radarhere · Pull Request #8794 · python-pillow/Pillow

# experimental access to the outline API
Outline: Callable[[], Image.core._Outline] | None
try:
Outline = Image.core.outline
except AttributeError:
Outline = None

The AttributeError here would have happened previously if WITH_ARROW was not defined in C.

#8211 removed the #ifdef WITH_ARROW however, and so now, it is always defined.