requestAndroidBuildVariants error

```
[zoneGuarded]: FormatException: Unexpected character (at character 2)
[!]
^

org-dartlang-sdk:///dart-sdk/lib/_internal/wasm/lib/convert_patch.dart 1654:5 fail
org-dartlang-sdk:///dart-sdk/lib/_internal/wasm/lib/convert_patch.dart 1520:9 parseNumber
org-dartlang-sdk:///dart-sdk/lib/convert/json.dart 641:11 convert
file:///Users/kenzieschmoll/develop/devtools/packages/devtools_app/lib/src/shared/server/_deep_links_api.dart 15:15 requestAndroidBuildVariants
org-dartlang-sdk:///dart-sdk/lib/_internal/wasm/lib/async_patch.dart 105:32 _awaitHelper
```

CC @chunhtai @hannah-hyj

从 packages/devtools_app/lib/src/shared/server/_deep_links_api.dart 中的 requestAndroidBuildVariants 开始，检查传递给 JSON 解析的响应。跟踪该请求并确定响应为什么以 "[!]" 开头；完成的标准是 Android 构建变体请求不再引发此 FormatException，并且其预期结果得到正确处理。

由索引模型根据 Issue 内容生成。