errorZone 属性

错误区域负责处理未捕获的错误。

这是离此区域最近的父区域，该区域提供了 handleUncaughtError 方法。

在 futures 中的异步错误不会在不同错误处理器的区域之间跨越区域边界。

示例

import 'dart:async';

main() {
  var future;
  runZonedGuarded(() {
    // The asynchronous error is caught by the custom zone which prints
    // 'asynchronous error'.
    future = Future.error("asynchronous error");
  }, (error) { print(error); });  // Creates a zone with an error handler.
  // The following `catchError` handler is never invoked, because the
  // custom zone created by the call to `runZonedGuarded` provides an
  // error handler.
  future.catchError((error) { throw "is never reached"; });
}

请注意，错误也无法进入具有不同错误处理器的子区域

import 'dart:async';

main() {
  runZonedGuarded(() {
    // The following asynchronous error is *not* caught by the `catchError`
    // in the nested zone, since errors are not to cross zone boundaries
    // with different error handlers.
    // Instead the error is handled by the current error handler,
    // printing "Caught by outer zone: asynchronous error".
    var future = Future.error("asynchronous error");
    runZonedGuarded(() {
      future.catchError((e) { throw "is never reached"; });
    }, (error, stack) { throw "is never reached"; });
  }, (error, stack) { print("Caught by outer zone: $error"); });
}