Support of container elements when using AppTest

Running streamlit 1.28.0 locally on python 3.9.

When testing the new AppTest functionnality on our app, I got this assertion error:

self = <[AttributeError("'Block' object has no attribute 'type'") raised in repr()] Block object at 0x7f1a5f41c400>
proto = 
root = {0: SpecialBlock(type='main', children={0: Header(tag='h2'), 1: Divider()}), 1: SpecialBlock(type='sidebar'), 2: SpecialBlock(type='event')}

    def __init__(
        proto: BlockProto | None,
        root: ElementTree,
        self.children = {}
        self.proto = proto
        if proto:
            ty = proto.WhichOneof("type")
            # TODO does not work for `st.container` which has no block proto
>           assert ty is not None
E           AssertionError

From what I understand, AppTest does not support st.container, which is an important part of a streamlit app. Is there any workaround, and if not, when do you think it will be supported ?

Thanks in advance.