After clearing the cache, the following exception occurs

## 🐛 Bug Report

### Expected behavior
After clearing the local cache, images can be loaded using the web image link

### Reproduction steps
Recursively delete local cache

### Configuration
`Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 1.22.5, on Mac OS X 10.12.6 16G29 darwin-x64, locale zh-Hans-CN)

[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.3)
[!] Xcode - develop for iOS and macOS (Xcode 9.0)
✗ Flutter requires a minimum Xcode version of 11.0.0.
Download the latest version or update via the Mac App Store.
! CocoaPods 1.6.1 out of date (1.8.0 is recommended).
CocoaPods is used to retrieve the iOS and macOS platform side's plugin code that responds to your plugin usage on the Dart side.
Without CocoaPods, plugins will not work on iOS or macOS.
For more info, see https://flutter.dev/platform-plugins
To upgrade:
sudo gem install cocoapods
[✓] Android Studio (version 3.6)
[!] IntelliJ IDEA Ultimate Edition (version 2019.3.5)
✗ Flutter plugin not installed; this adds Flutter specific functionality.
✗ Dart plugin not installed; this adds Dart specific functionality.
[✓] VS Code (version 1.53.0)
[✓] Connected device (1 available)

! Doctor found issues in 2 categories.`
**Version:** 2.2.0+1

**Platform:**
- [❎ ] :iphone: iOS
- [❎ ] :robot: Android