Minor cleanup of some context manager stuff and better handling of GetItemOrAttribute.

[sfc-gh-dkurokawa]

Description

Minor cleanup of some context manager stuff and better handling of GetItemOrAttribute.

Other details good to know for developers

This is kinda a mish-mash of some stuff, but is just some more stuff I'm pulling from Piotr's PR.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to
  not work as expected)
• New Tests
• This change includes re-generated golden test results
• This change requires a documentation update

---

Important

Improves context manager exception handling and refines GetItemOrAttribute logic, with minor docstring formatting changes.

• Context Manager Handling:
  • In app.py, __exit__ and __aexit__ methods now return False to not suppress exceptions.
• GetItemOrAttribute Handling:
  • In serial.py, GetItemOrAttribute.get() now checks for __getitem__ instead of Dict.
• Docstring Formatting:
  • Minor formatting changes in docstrings in base.py.

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