Flutter常用的错误图片占位组件

```java
  // 构建错误图片占位符
  Widget _buildErrorImage() {
    return Container(
      width: 120,
      height: 80,
      decoration: BoxDecoration(
        color: Colors.grey.shade200,
        borderRadius: BorderRadius.circular(8),
      ),
      child: Icon(
        Icons.image_not_supported_outlined,
        size: 40,
        color: Colors.grey.shade400,
      ),
    );
  }
```

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