Split tables not displayed on first load

[jpmckinney]

Actual behavior: When uploading the 2021-03-03.json fixture and selecting the awards table, the Preview tables screen initially only shows the awards table. Attempting to toggle Keep arrays in main table displays an error, and then displays the awards_suppliers and awards_items tables.

Expected behavior: The other 2 tables should be displayed initially, and the toggle should be disabled.

This error is related to the two failing tests in the docker job (in the CI workflow).

Once fixed, we can remove continue-on-error from the workflow.

Not sure if #381 is related.