Changelog

Fixed guest import crash when an email is shared by multiple guests

Importing a CSV row whose email already belonged to two or more guests in the event failed with 'Multiple rows were found when one or none was required'. The error was raised by the informational check that reports shared emails as allowed: it used a single-row query helper that throws when several guests share the address — precisely the corporate/family scenario the import supports. That check, the exact-duplicate detection, and the equivalent check in single guest creation now tolerate multiple matches. Additionally, import error display was improved: technical exceptions are translated into user-friendly messages (raw SQL text never reaches the user), and the Import Results error table now shows row number, guest identity and a meaningful category (Duplicate / Invalid email / Missing data / Conflict) instead of arbitrary words. Verified by reproducing the exact scenario: two guests sharing an email, then importing a third with the same address — previously crashed, now imports with the shared-email notice.