[Resolve #1484] Gracefully handle invalid parameters

This adds logic to _cast_parameters to also handle the case that the parameters dict itself is not a dict but some other invalid type.

PR Checklist

[x] Wrote a good commit message & description [see guide below].
[x] Commit message starts with [Resolve #issue-number].
[x] Added/Updated unit tests.
[x] Added/Updated integration tests (if applicable).
[x] All unit tests (poetry run tox) are passing.
[x] Used the same coding conventions as the rest of the project.
[x] The new code passes pre-commit validations (poetry run pre-commit run --all-files).
[x] The PR relates to only one subject with a clear title. and description in grammatically correct, complete sentences.