var value: SuccessThe result from a throwing task, after it completes.
var result: Result<Success, Failure>The result or error from a throwing task, after it completes.
Discussion 解説
If the task hasn’t completed yet, accessing this property waits for it to complete and its priority increases to that of the current task. Note that this might not be as effective as creating the task with the correct priority, depending on the executor’s scheduling details. これはタスクを正しい優先度で作成するのと同じくらい効果的でないかもしれないことに注意してください、エグゼキュータのもつ予定の仕方の詳細に依存しています。
Tasks that never throw an error can still check for cancellation, but they need to use an approach like returning nil instead of throwing an error.