Return empty Much() when encountering an unknown class #5457

Job	Run time
Shellcheck	3s
Prepare	1m 3s
Dependency	6s
Ruff check and force	14s
Check commit	37s
Create pytest cache for Python 3.13.0	18s
Create pytest cache for Python 3.12	8s
Run pytest using Python 3.13.0	21s
Run pytest using Python 3.12	12s
Run mypy	24s
Process test coverage	24s
Process test complexity	14s
Build and publish Python 🐍 distributions 📦 to TestPyPI	28s
	4m 32s

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