Flutter 异步文件读取异常处理

我对dart /Flutter 翼还是个新手，对这种情况下的async-awaitFlutter 翼异常处理有点困惑.

所以基本上我有这个功能，从Flutter 数据文件夹加载一个.json设置文件. 它应该加载设置，并在无法找到文件的情况下抛出SettingsLoadingException异常，这样调用函数就知道何时创建新的文件.

这种机制是有效的，但在这种情况下，有两件事让我感到困惑.首先，它仍然打印一个未捕获的FileSystemException到控制台，即使打印"没有设置文件！"说明它被抓到了.其次，"没有设置文件"和错误被打印了两次-那么它是否捕捉到了两个错误？

Future<Settings> loadSettings() async {
  try {
    String fileName = SettingsService.settingsFileName;
    File file = File("${await _localPath}/${dbFolderName}/${fileName}");

    String fileContent = await file.readAsString();
    Map<String, dynamic> settingJsonMap = jsonDecode(fileContent);
    Settings settings = Settings.fromJson(settingJsonMap);

    return settings;
  } catch (e) {
    print("No settings file!");
    throw SettingsLoadingException("Unable to load settings");
  }
}

I/flutter (10533): No settings file!
I/flutter (10533): No settings file!
E/flutter (10533): \[ERROR:flutter/runtime/dart_vm_initializer.cc(41)\] Unhandled Exception: FileSystemException: Cannot open file, path = '/data/user/0/com.yapps.smartdart/app_flutter/db/settings.json' (OS Error: No such file or directory, errno = 2)
E/flutter (10533): #0      \_File.open.\<anonymous closure\> (dart:io/file_impl.dart:356:9)
E/flutter (10533): \<asynchronous suspension\>
E/flutter (10533):
E/flutter (10533): \[ERROR:flutter/runtime/dart_vm_initializer.cc(41)\] Unhandled Exception: FileSystemException: Cannot open file, path = '/data/user/0/com.yapps.smartdart/app_flutter/db/settings.json' (OS Error: No such file or directory, errno = 2)
E/flutter (10533): #0      \_File.open.\<anonymous closure\> (dart:io/file_impl.dart:356:9)
E/flutter (10533): \<asynchronous suspension\>
E/flutter (10533):
E/SurfaceSyncer(10533): Failed to find sync for id=0
W/Parcel  (10533): Expecting binder but got null!

我已经try 使用.Then和.catchError API，但都不起作用，导致了一个完全不同的错误.