If a file cannot be thumbnailed for some reason (e.g. the file is empty), then
catch the exception and convert it to a reasonable error message for the client.
The CI appears to use the latest version of isort, which is a problem when isort gets a major version bump. Rather than try to pin the version, I've done the necessary to make isort5 happy with synapse.
Pillow will use nearest neighbour as the resampling algorithm if the
source image is either 1-bit or a color palette using 8 bits. If we
convert to RGB before scaling, we'll probably get a better result.
Python will return a tuple whether there are parentheses around the returned values or not.
I'm just sick of my editor complaining about this all over the place :)
