Crashed when I run the demo," _cacheData.containsKey(url) ",_cacheData is null

[hasonguo]

The following NoSuchMethodError was thrown resolving an image codec:
flutter: The method 'containsKey' was called on null.
flutter: Receiver: null
flutter: Tried calling: containsKey("http://via.placeholder.com/350x200")
flutter:
flutter: When the exception was thrown, this was the stack:
flutter: #0 Object.noSuchMethod (dart:core/runtime/libobject_patch.dart:46:5)
flutter: #1 CacheManager.getFile (package:example/flutter_cache_manager.dart:202:21)
flutter:
flutter: #2 CachedNetworkImageProvider._loadAsync (package:example/cached_network_image.dart:474:35)
flutter:

code below:

Future getFile(String url, {Map<String, String> headers}) async {
String log = "[Flutter Cache Manager] Loading $url";

if (!_cacheData.containsKey(url)) {
  await _lock.synchronized(() {
    if (!_cacheData.containsKey(url)) {
      _cacheData[url] = new CacheObject(url);
    }
  });
}

[renefloor]

This is fixed now