DRYD-1608: Use coalesce to avoid null error

[mikejritter]

What does this do?

• Use coalesce on parties involved fields

Why are we doing this? (with JIRA link)
Jira: https://collectionspace.atlassian.net/browse/DRYD-1608

Previously we updated the parties involved to aggregate all parties instead of a single. We forgot to update the query to coalesce against an empty array in order for the JS expression to work without needing additional null checks.

How should this be tested? Do these changes have associated tests?

• Redeploy the report
• Create a single Summary Documentation
• Run the Notice of Intent to Repatriate report

Dependencies for merging? Releasing to production?
None

Has the application documentation been updated for these changes?
No

Did someone actually run this code to verify it works?
@mikejritter tested locally