fix: copy some fixes from 1.8-release-branch
Things addressed:
- fixes a graphql error in the logs when someone views the manuscripts page without yet being a member of the system-wide chat (copied from this commit)
- fails gracefully if there is no email template configured for a system-generated email: otherwise we had exceptions that interfered with the user workflow. Copied from !928 (merged).
- fixed review bug that caused a reviewer not to see all shared reviews but showed them spurious blank reviews (#1355 (closed)). Copied from !923 (merged).