Develop/fixes/dlsv2 687 page 500 error on choose working group members screen when given user email not associated with dls account and clicking the add as contributor or reviewer buttons

[OluwatobiAwe]

JIRA link

DLSV2-687

Description

Display of proper error message at the top of the page and by the textbox
The error message should go off the page on refresh
**The content of the textbox should be persisted after the server responds with an error message.

Screenshots

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Developer checks

(Leave tasks unticked if they haven't been appropriate for your ticket.)

I have:

• Run the formatter and made sure there are no IDE errors (see info on Text Editor settings to avoid whitespace changes)
• Written tests for the changes (accessibility tests, unit tests for controller, data services, services, view models, etc)
• Manually tested my work with and without JavaScript
• Tested any Views or partials created or changed with Wave Chrome plugin and addressed any valid accessibility issues
• Updated/added documentation in Confluence and/or GitHub Readme. List of documentation links added/changed:
  • doc_1_here
• Updated my Jira ticket with information about other parts of the system that were touched as part of the MR and have to be sanity tested to ensure nothing’s broken
• Scanned over my own MR to ensure everything is as expected and it looks right in the browser