bugfix: reporter is optional on update flow, reporter can be None

[wssheldon]

Resolves:

AttributeError
"'NoneType' object has no attribute 'individual'"

From:

    case_flows.case_update_flow(
        case_id=case.id,
        previous_case=previous_case,
        db_session=db_session,
        reporter_email=case.reporter.individual.email, <-------
        assignee_email=assignee_email,
        organization_slug=context["subject"].organization_slug,
    )

Solution:

Reporter is optional on cases, it can be None.

[wssheldon]

May need to be handled here too:

    if case.tactical_group:
        # we update the tactical group
        for group_member in [reporter_email, assignee_email]:
            group_flows.update_group(
                subject=case,
                group=case.tactical_group,
                group_action=GroupAction.add_member,
                group_member=group_member,
                db_session=db_session,
            )