Mypy 1.0.0 crashes with asyncssh

[julian-r]

Crash Report

Updated my project from mypy 0.991 to 1.0.0

Traceback

On the top you see the log because my execution with --verbose

LOG:  Writing asyncssh.connection /Users/julian/Library/Caches/pypoetry/virtualenvs/mypy-asyncssh-issue-ZzvwNVve-py3.11/lib/python3.11/site-packages/asyncssh/connection.py asyncssh/connection.meta.json asyncssh/connection.data.json
LOG:  Build finished in 1.795 seconds with 270 modules, and 0 errors
Traceback (most recent call last):
  File "/Users/julian/Library/Caches/pypoetry/virtualenvs/mypy-asyncssh-issue-ZzvwNVve-py3.11/bin/mypy", line 8, in <module>
    sys.exit(console_entry())
             ^^^^^^^^^^^^^^^
  File "/Users/julian/Library/Caches/pypoetry/virtualenvs/mypy-asyncssh-issue-ZzvwNVve-py3.11/lib/python3.11/site-packages/mypy/__main__.py", line 15, in console_entry
    main()
  File "mypy/main.py", line 95, in main
  File "mypy/main.py", line 174, in run_build
  File "mypy/build.py", line 194, in build
  File "mypy/build.py", line 277, in _build
  File "mypy/build.py", line 2923, in dispatch
  File "mypy/build.py", line 3320, in process_graph
  File "mypy/build.py", line 3443, in process_stale_scc
  File "mypy/build.py", line 2504, in write_cache
  File "mypy/build.py", line 1574, in write_cache
  File "mypy/nodes.py", line 377, in serialize
  File "mypy/nodes.py", line 3841, in serialize
  File "mypy/nodes.py", line 3778, in serialize
  File "mypy/nodes.py", line 3514, in serialize
  File "mypy/types.py", line 2072, in serialize
  File "mypy/types.py", line 605, in serialize
  File "mypy/types.py", line 2876, in serialize
AssertionError: Internal error: unresolved placeholder type None

To Reproduce

I've provided a poetry-based project which will cause the error when

poetry run mypy --verbose --show-traceback .

Your Environment

Project to reproduce:
https://github.com/julian-r/mypy-asyncssh-issue

• Mypy version used: 1.0.0
• Mypy command-line flags: --verbose --show-traceback
• Mypy configuration options from mypy.ini (and other config files): none
• Python version used: 3.11.2
• Operating system and version: macOS 13.1 (22C65) M1

[AlexWaygood]

Duplicate of #14631

[AlexWaygood]

A patch release with the fix should be coming soon!

[julian-r]

Thank you! You are doing awesome work! :)