Error performing build runner

When I run this `flutter pub run build_runner build --delete-conflicting-outputs` , it's giving this error. I'm not sure why it's building for all the files. The below files are all widgets.
```
type 'UnspecifiedInvalidResult' is not a subtype of type 'LibraryElementResult' in type cast
[SEVERE] built_value_generator:built_value on lib/views/call/utils/toolbar.dart:

type 'UnspecifiedInvalidResult' is not a subtype of type 'LibraryElementResult' in type cast
[SEVERE] built_value_generator:built_value on lib/views/chat/chat_screen_heder_screen/chat_search.dart:

```

Using
```
built_value: ^8.1.3
built_collection: ^5.1.1

built_value_generator: ^8.1.0
build_runner: ^2.1.5
```