找出 Event 解码器里的 bug

import Foundation

struct Event: Decodable {
    let eventId: Int
    let startsAt: Date
}

let data = Data(#"{"event_id":7,"starts_at":"2026-06-01T10:00:00Z"}"#.utf8)
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
let event = try decoder.decode(Event.self, from: data)
print(event.eventId)