test('should emit [Error] when the inpus is invalid.'...)

Whatever I put into expected, this test always passed. Should it?

type 'Null' is not a subtype of type 'Future'
package:internet_connection_checker/internet_connection.dart 184:20 MockInternetConnectionChecker.hasConnection
test/core/network_info_test.dart 23:42 main..

Error while send 08 number and use de green button.

Failed assertion: line 137 pos 7: '!_isCompleted':
package:bloc/src/bloc.dart:137
2
E/flutter (14410):
E/flutter (14410): emit was called after an event handler completed normally.
E/flutter (14410): This is usually due to an unawaited future in an event handler.
E/flutter (14410): Please make sure to await all asynchronous operations with event handlers
E/flutter (14410): and use emit.isDone after asynchronous operations before calling emit() to
E/flutter (14410): ensure the event handler has not completed.
E/flutter (14410):
E/flutter (14410): BAD
E/flutter (14410): on((event, emit) {
E/flutter (14410): future.whenComplete(() => emit(...));
E/flutter (14410): });

code ...

assert(
!_isCompleted,
'''\n\n
emit was called after an event handler completed normally.
This is usually due to an unawaited future in an event handler.
Please make sure to await all asynchronous operations with event handlers
and use emit.isDone after asynchronous operations before calling emit() to
ensure the event handler has not completed.

BAD
on((event, emit) {
future.whenComplete(() => emit(...));
});

package:test_api expect
package:flutter_test/src/widget_tester.dart 460:16 expect
test\features\number_trivia\data\models\number_trivia_model_test.dart 23:11 main..

Expected: NumberTriviaModel:
Actual: NumberTriviaModel: