raise exception on invalid images (#999)
# What does this PR do?
This PR is meant to handle cases in which the images provided are
invalid.
## Who can review?
Anyone in the community is free to review the PR once the tests have
passed. Feel free to tag
members/contributors who may be interested in your PR.
@Narsil
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Co-authored-by: Nicolas Patry <patry.nicolas@protonmail.com>
