[BUG] app cannot build

[ikuruzum]

Describe the bug:
it does not work

HTML to reproduce the issue:
flutter_html: 3.0.0-beta.2
flutter_html_all: ^3.0.0-alpha.6
add these two in pubspec.yaml

Stacktrace/Logcat

Launching lib/main.dart on POT LX1 in debug mode...
../../.pub-cache/hosted/pub.dev/flutter_html_math-3.0.0-alpha.4/lib/flutter_html_math.dart:11:1: Error: Type 'CustomRender' not found.
CustomRender mathRender({OnMathError? onMathError}) =>
^^^^^^^^^^^^
../../.pub-cache/hosted/pub.dev/flutter_html_math-3.0.0-alpha.4/lib/flutter_html_math.dart:35:1: Error: Type 'CustomRenderMatcher' not found.
CustomRenderMatcher mathMatcher() => (context) {
^^^^^^^^^^^^^^^^^^^
../../.pub-cache/hosted/pub.dev/flutter_html_math-3.0.0-alpha.4/lib/flutter_html_math.dart:12:5: Error: Undefined name 'CustomRender'.
    CustomRender.widget(widget: (context, buildChildren) {
    ^^^^^^^^^^^^
Target kernel_snapshot failed: Exception

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUİLD FAILED in 27s
Exception: Gradle task assembleDebug failed with exit code 1