Function insert 

pub async fn insert(
    conn: &mut PgConnection,
    user_id: Option<Uuid>,
    report: &NewErrorReport,
) -> ModelResult<Uuid>

Inserts one error occurrence and upserts its variant in a single transaction. The variant service is treated as immutable after creation; any future service rename must update both error_variants.service and related error_occurrences.service in the same transaction.