graph_datasets download has unhandled exception when directory does not exist

[cwpearson]

Version Information

version: 0.6.0-rc2
sha:     32319c4e4d4f5dcc9af97ac8fbb9fd9b8c79a04f
author:  Carl Pearson
url:     https://github.com/cwpearson/graph-datasets2

Describe the bug

NOTICE checking SparseChallenge/sparse-images-1024/
NOTICE downloading SparseChallenge/sparse-images-1024/
NOTICE download https://graphchallenge.s3.amazonaws.com/synthetic/sparsechallenge_2019/mnist/sparse-images-1024.tsv.gz
oserr.nim(94)            raiseOSError
asyncfutures.nim(374)    read
Error: unhandled exception: No such file or directory [OSError]

To Reproduce

./graph_datasets download sparse-images-1024

Expected behavior
If the target directory does not exist, this command should create it.

Screenshots
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Environment Information

• OS: macOS 10.14.6
• Architecture: amd64

Additional context
Add any other context about the problem here.