Editor: No agency_id with multiple agencies results in network error

[philip-cline]

Observed behavior (please include a screenshot if possible)

When creating more than one agency in the Editor, the agency_id field must be filled out. However, it is not highlighted as a mandatory field and saving the new agency will result in a network (500) error, rather than indicating that the agency_id field should be filled out:

Expected behavior

Instead, the error should be properly caught and a message prompting the user to input an agency_id for the new agency should be displayed. Further, upon creating a new agency, the agency_id field should be displayed as mandatory if there is already an existing agency.

Steps to reproduce the problem

Agencies -> New Agency -> Fill out relevant values except agency_id -> Save -> Error will be displayed

Version of datatools-ui and datatools-server if applicable (exact commit hash or branch name)

Info below: UI Version: | b3f79a UI deployed at: | June 4, 2020 11:30 AM Server version: | 3ac5c3