Variables w and h possibly unassigned during JPEG image size computation

[laclouis5]

I'm using this code in a project and while running the linter with type checking enabled (Pylint) I found what look like an error in the decoding of the image size of the JPEG variant here:

image_size/get_image_size.py

Lines 144 to 171 in fb25377

	elif (size >= 2) and data.startswith(b'\377\330'):
	# JPEG
	imgtype = JPEG
	input.seek(0)
	input.read(2)
	b = input.read(1)
	try:
	while (b and ord(b) != 0xDA):
	while (ord(b) != 0xFF):
	b = input.read(1)
	while (ord(b) == 0xFF):
	b = input.read(1)
	if (ord(b) >= 0xC0 and ord(b) <= 0xC3):
	input.read(3)
	h, w = struct.unpack(">HH", input.read(4))
	break
	else:
	input.read(
	int(struct.unpack(">H", input.read(2))[0]) - 2)
	b = input.read(1)
	width = int(w)
	height = int(h)
	except struct.error:
	raise UnknownImageFormat("StructError" + msg)
	except ValueError:
	raise UnknownImageFormat("ValueError" + msg)
	except Exception as e:
	raise UnknownImageFormat(e.__class__.__name__ + msg)

More specifically, if the if branch at line 156 is not triggered, the variables h and w are not assigned any value. Thus, line 164 and 165 fails and the image size cannot be computed. Is there something missing in the else branch?