crash on tuple expansion in try/except block

[neutrinoceros]

Running flake8 against the following file produces no report as an exception is raised in bugbear

# dummy.py
grey_list = (ValueError,)
black_list = (TypeError,)

try:
    int("1e3")
except (*grey_list, *black_list):
    print("error caught")

crashes with

Traceback (most recent call last):
...
  File "/Users/clm/.pyenv/versions/3.8.6/envs/yt_dev/lib/python3.8/site-packages/bugbear.py", line 126, in _to_name_str
    assert isinstance(node, ast.Attribute)
AssertionError

For information

$ flake8 --version
3.8.4 (flake8-bugbear: 20.11.1, mccabe: 0.6.1, pycodestyle: 2.6.0, pyflakes: 2.2.0) CPython 3.8.6 on Darwin

[neutrinoceros]

I've started looking around for a solution and I notice that bugbear relies on hypothesmith to check that it doesn't crash on "any" valid code, but I guess hypothesmith.from_grammar() doesn't ever generate something like this. I'm going to try and solve the issue in bugbear but it should be reported upstream at some point.