PVector angleBetween returns 0 when x and y of either parameter are both 0

I found an existing report describing similar behavior with 3D PVectors (https://github.com/processing/processing/issues/2045), but it appears the same problem affects 2D PVectors as well.

When either the start or end PVector is (0,0) the output of angleBetween() is always 0.

I'm not particularly experienced with Processing, so it's entirely possible that I'm misunderstanding something or using the API incorrectly. I tend to pick it up every few months for small projects and then promptly forget most of what I learned.

That said, I've spent some time testing this behavior and looking into the implementation, and based on what I found, I would not expect the angle to be 0 in the cases I tested.

Edit: I forgot to add, I'm using processing 4.5.2

Bắt đầu tại điểm vào PVector.angleBetween() và so sánh hành vi 2D với báo cáo 3D liên quan trong issue #2045. Làm rõ kết quả mong đợi khi một trong hai vector là (0,0), sau đó xác minh hành vi đã được sửa bằng coverage hồi quy cho các trường hợp đó.