Don't pass nil email address to EmailChecker

[CatalinVoineag]

Context

In production we have over 12k application references with nil email addresses.

The EmailChecker class expects an email and not a nil value. This creates a few exceptions when a candidate inputs a reference.

The form is saved to DB once the candidate adds a name to the reference, if the candidate moves on, the reference is saved in DB, without a email. So this might be a way we got 12k references without an email.

This commit tries to make sure this class doesn't receive a nil parameter.

https://dfe-teacher-services.sentry.io/issues/6047049953/events/ce842c5fdcad4b9d91787920e1098f91/?environment=production&project=1765973&query=is%3Aunresolved%20issue.priority%3A%5Bhigh%2C%20medium%5D&referrer=previous-event&statsPeriod=24h&stream_index=2

Changes proposed in this pull request

Guidance to review

Things to check

• If the code removes any existing feature flags, a data migration has also been added to delete the entry from the database
• This code does not rely on migrations in the same Pull Request
• If this code includes a migration adding or changing columns, it also backfills existing records for consistency
• If this code adds a column to the DB, decide whether it needs to be in analytics yml file or analytics blocklist
• API release notes have been updated if necessary
• If it adds a significant user-facing change, is it documented in the CHANGELOG?
• Required environment variables have been updated added to the Azure KeyVault
• Inform data insights team due to database changes
• Make sure all information from the Trello card is in here
• Rebased main
• Cleaned commit history
• Tested by running locally
• Add PR link to Trello card

[elceebee]

This is an interesting problem. I deliberately required the email_address for the EmailChecker, as I assumed there would be so few without email addresses, we would want it to error if the email address wasn't there. I do wonder how we ended up with 12k!

[dcyoung-dev]

Should there be a validation on the Reference model?

[CatalinVoineag]

Should there be a validation on the Reference model?

We can't do this. The form saves to DB when a name is added to a reference. That's how you can end up a reference without an email address. You add a name to a reference and you don't continue adding a email. The reference is now in DB without an email address.