Subgraphs cause a black.parsing.InvalidInput error.

[FleetingOrchard]

As title. Ref. the following exception:

    final_code = black.format_str(final_code, mode=black.Mode())
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "src\black\__init__.py", line 1208, in format_str
  File "src\black\__init__.py", line 1222, in _format_str_once
  File "src\black\parsing.py", line 98, in lib2to3_parse
black.parsing.InvalidInput: Cannot parse: 164:88:               regexreplace_173:132 = regexreplace.execute(string=get_value_at_index(regexreplace_173:130, 0), regex_pattern="!S2(?P<inner>[^!]*)!", replace="\g<inner>", case_insensitive=True, multiline=True, dotall=False, count=0)

In the tested workflow, that regexreplace node is inside a subgraph. Unpacking the subgraph causes the exception to then show up referencing another node in another subgraph.