Fix stubtest and other mypy errors

Author: saulshanabrook

pyproject.toml

@@ -246,6 +246,7 @@ warn_redundant_casts = true
 warn_unused_ignores = true
 strict_equality = true
 extra_checks = true
+strict_equality_for_none = true
 
 [tool.maturin]
 python-source = "python"