Fix mypy tests. Looks like the tests are error order sensitive

[euresti]

Fixes #855

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• Added tests for changed code.
• New features have been added to our Hypothesis testing strategy.
• Changes or additions to public APIs are reflected in our type stubs (files ending in .pyi).
  • ...and used in the stub test file tests/typing_example.py.
• Updated documentation for changed code.
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[hynek]

Thank you so much!