fix: Handle existing branding localization for PhishProtection standard

[ZenTopBrandon]

Summary

Fixes misleading errors from the PhishProtection standard when the tenant's default branding localization already exists but has no custom CSS.

Previously, the standard used the response from /branding/localizations/0/customCSS to infer whether the default localization existed. An existing localization with no custom CSS was therefore treated as missing, causing CIPP to attempt to create localization ID 0 again.

Microsoft Graph correctly rejected that request with:

Another object with the same value for property id already exists.

The standard subsequently applied the CSS successfully, but the recovered creation conflict remained in the Logbook at Error severity and could make the standard appear to have failed.

Changes

• Query the tenant's branding localizations and explicitly check for localization ID 0.
• Reuse the existing default localization when it is already present.
• Create the default localization only when ID 0 is absent.
• Treat only the specific Graph Request_BadRequest / ObjectConflict response targeting id as a recovered race condition.
• Log that recovered condition at Info severity.
• Preserve Error severity and diagnostic data for all other localization creation failures.
• Continue applying the PhishProtection custom CSS after a recovered conflict.

Why retain conflict handling after the existence check?

The existence check prevents the normal duplicate-create case, but another process could create localization ID 0 between the GET and POST requests.

The targeted ObjectConflict handling covers that race without suppressing unrelated Graph failures.

Tests

Added Pester coverage for:

• An existing default localization with empty custom CSS.
• Creating the default localization when ID 0 is absent.
• Recovering from the specific duplicate-ID race without writing a misleading Error.
• Retaining Error severity for unexpected localization creation failures.

[github-actions]

✅ PR title follows Conventional Commits

Received: fix: Handle existing branding localization for PhishProtection standard

Thanks for fixing it!