Error on accessing unset optional field

[124C41p]

On main branch, the proto message

message Foo {
    optional int32 a = 1;
}

is compiled to

@dataclass(eq=False, repr=False)
class Foo(betterproto.Message):
    a: Optional[int] = betterproto.int32_field(1, optional=True, group="_a")

Now both Foo().a and Foo(a=None).a raises the same AttributeError: '_a' is set to None, not 'a' . This is probably unwanted behavior?

It seems to be fixed by removing the term group="_a" manually. Is there a reason to set the group in this case in the first place?

[124C41p]

Related to #499