iOS StateProvider crash

Doing Https.request, got error:
Alamofire/SessionDelegate.swift:49: Fatal error: StateProvider is nil for task 1.

Relevant Stack:

#4	0x00000001a28e5b54 in assertionFailure ()
#5	0x000000010610bc2c in SessionDelegate.request<Alamofire.DataRequest>(for:as:) at /Users/chris/Projects/Mantis/mantis_laser_trainer_app/platforms/ios/Pods/Alamofire/Source/Core/SessionDelegate.swift:49
#6	0x000000010610f40c in SessionDelegate.urlSession(_:dataTask:didReceive:) at /Users/chris/Projects/Mantis/mantis_laser_trainer_app/platforms/ios/Pods/Alamofire/Source/Core/SessionDelegate.swift:254

Code:

    func request<R: Request>(for task: URLSessionTask, as type: R.Type) -> R? {
        guard let provider = stateProvider else {
            assertionFailure("StateProvider is nil for task \(task.taskIdentifier).")
            return nil
        }

        return provider.request(for: task) as? R
    }

まず Https.request の失敗を再現し、Alamofire's platforms/ios/Pods/Alamofire/Source/Core/SessionDelegate.swift 周辺のライフサイクル、特に 49 行目と 254 行目を追跡します。data-task callback が実行されるときに stateProvider が nil になる理由を特定します。この request path で crash が解消され、適切な regression check によって失敗がカバーされれば完了です。