Prevent hub/documents confirm page from crashing if there is no tax return

[embarnard]

Link to pivotal/JIRA issue

• e.g. https://codeforamerica.atlassian.net/browse/GYR1-910

Is PM acceptance required? (delete one)

• Yes - don't merge until JIRA issue is accepted!

Reminder: merge main into this branch and get green tests before merging to main

What was done?

• add documents page in the hub doesn’t require that you select a tax return, so if you submit that field blank there will be no tax year on the confirm page and it will error out
• prevent page from erroring if document has no tax return

How to test?

Screenshots (for visual changes)

• Before

• After

[github-actions]

Heroku app: https://gyr-review-app-6167-dec27892ec22.herokuapp.com/
View logs: heroku logs --app gyr-review-app-6167 (optionally add --tail)

[spompea-cfa]

lgtm