Two bugs in Smooth geoblock

[caspervdw]

From: https://nelen-schuurmans.atlassian.net/browse/BACK-366

https://sentry.io/organizations/nens/issues/1111837410

I could reproduce it from the console:

from geoblocks.raster import RasterStoreSource, Clip, Smooth
source = RasterStoreSource("file:///119-fs-c02/raster-production/stores/nelen-schuurmans/windkaart_nlv2")
smooth = Smooth(source, 50, 0)
req = {'bbox': [516246, 6706385, 521405, 6703400], 'height': 256, 'mode': 'vals', 'projection': 'EPSG:3857', 'start': None, 'stop': None, 'width': 256}
source_data = source.get_data(**req)
smooth_data = smooth.get_data(**req)
source_data['values'].shape
(1, 256, 256)
smooth_data['values'].shape
(1, 4, 256)

Another bug is: when handling a Point request, “shape_m” could be 0 in expand_request_meters, leading to ZeroDivisionError. --> #3706