Area.union() not computed correctly in some cases

[FoamyGuy]

This code:

from displayio._area import Area

area1 = Area(18, 0, 24, 12)
area2 = Area(0, 0, 0, 12)

print(f"area1 = {area1}")
print(f"area2 = {area2}")

area1.union(area2, area1)

print(f"area1 = {area1}")
print(f"area2 = {area2}")

Results in this output:

area1 = Area TL(18,0) BR(24,12)
area2 = Area TL(0,0) BR(0,12)
area1 = Area TL(0,0) BR(0,12)
area2 = Area TL(0,0) BR(0,12)

area1 gets "zero'd out" instead of being modified to contain the full union of the input areas.

This is due to the if statments and early returns here:

Adafruit_Blinka_Displayio/displayio/_area.py

Lines 89 to 94 in c35bd2c

	if self.empty():
	self.copy_into(union)
	return
	if other.empty():
	other.copy_into(union)
	return

I don't think that I understand what the original intended purpose of those checks and early returns are but I believe in this case it's causing it to copy the empy area into the union output area which results in the output being smaller than the union of the two inputs.