Unnecessary nullable on dynamic fields.

[luis901101]

Describe the issue
Unnecessary nullable on dynamic fields.
If I have a filed like dynamic data the generated code will use dynamic? data in the _$MyClassCWProxy implementation.

Paste the package version.

dependencies:
  copy_with_extension: ^5.0.0
dev_dependencies:
  copy_with_extension_gen: ^5.0.0

To Reproduce
Steps to reproduce the behaviour:

@CopyWith(skipFields: true)
class MyClass {
  dynamic data;

  MyClass({
    this.data,
  });
}

Expected behaviour
Avoid using unnecessary ? on dynamic fields.

[luis901101]

Another issue with dynamic fields I just faced is this:

MyClass call({
    dynamic? data,
  });

MyClass call({
    Object? data = const $CopyWithPlaceholder(),
  }) {
    return MyClass(
      data: data == const $CopyWithPlaceholder() || data == null
          // ignore: unnecessary_non_null_assertion
          ? _value.data!
          // ignore: cast_nullable_to_non_nullable
          : data as dynamic,
    );
  }

Specifically the _value.data! and the previous condition data == null, so when data is null and I use: var copyInstance = instance.copyWith(); NullPointerException throws.

I think generated code should look like:

MyClass call({
    dynamic data,
  });

MyClass call({
    Object? data = const $CopyWithPlaceholder(),
  }) {
    return MyClass(
      data: data == const $CopyWithPlaceholder()
          // ignore: unnecessary_non_null_assertion
          ? _value.data
          // ignore: cast_nullable_to_non_nullable
          : data as dynamic,
    );
  }

[numen31337]

This comment describes crash from #74.

The initial message is another issue about this:

TestNullability call({
  int? nullableWithNonNullableConstructor,
  dynamic? dynamicField, /// <--- ISSUE, dynamic? makes no sense.
  List<int>? integers,
});

// info • test/gen_nullability_test.g.dart:25:12 • The '?' is unnecessary because 'dynamic' is nullable without it. • unnecessary_question_mark