materialapp.body.dart

Query(
  options: QueryOptions(
    documentNode: CompaniesDataQuery().document,
  ),
  builder: (
    QueryResult result, {
    Future<QueryResult> Function() refetch,
    FetchMore fetchMore,
  }) {
    if (result.hasException) {
      return Text(result.exception.toString());
    }

    if (result.loading) {
      return const Center(
        child: CircularProgressIndicator(),
      );
    }

    final allCompanies = CompaniesData.fromJson(result.data).allCompanies;

    return ListView.builder(
      itemBuilder: (_, index) {
        return ListTile(
          leading: Icon(Icons.card_travel),
          title: Text(allCompanies[index].name),
          subtitle: Text(allCompanies[index].industry),
        );
      },
      itemCount: allCompanies.length,
    );
  },
)

небольшая опечатка в примере

final allCompanies = CompaniesData.fromJson(result.data).allCompanies;
# надо
final allCompanies = CompaniesData$Query.fromJson(result.data).allCompanies;