CLN: assorted
- [ ] closes #xxxx (Replace xxxx with the Github issue number)
- [ ] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [ ] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [ ] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

```
mypy.....................................................................Failed
- hook id: mypy
- exit code: 1

pandas/core/arrays/datetimes.py:2528: error: Argument 1 to "Timestamp" has incompatible type "Optional[Timestamp]"; expected "Union[integer[Any], float, str, date, datetime64]"  [arg-type]
pandas/core/arrays/datetimes.py:2529: error: Non-overlapping identity check (left operand type: "Timestamp", right operand type: "NaTType")  [comparison-overlap]
pandas/core/arrays/datetimes.py:2530: error: Argument 1 to "Timestamp" has incompatible type "Optional[Timestamp]"; expected "Union[integer[Any], float, str, date, datetime64]"  [arg-type]
pandas/core/arrays/datetimes.py:2531: error: Non-overlapping identity check (left operand type: "Timestamp", right operand type: "NaTType")  [comparison-overlap]
pandas/core/arrays/datetimes.py:2534: error: Incompatible types in assignment (expression has type "datetime", variable has type "Optional[Timestamp]")  [assignment]
pandas/core/arrays/datetimes.py:2537: error: Incompatible types in assignment (expression has type "datetime", variable has type "Optional[Timestamp]")  [assignment]
pandas/core/arrays/datetimes.py:2539: error: Unsupported operand types for < ("Timestamp" and "None")  [operator]
pandas/core/arrays/datetimes.py:2539: error: Unsupported operand types for > ("Timestamp" and "None")  [operator]
pandas/core/arrays/datetimes.py:2539: error: Unsupported left operand type for < ("None")  [operator]
pandas/core/arrays/datetimes.py:2539: note: Both left and right operands are unions
pandas/core/arrays/datetimes.py:2544: error: No overload variant of "__radd__" of "BaseOffset" matches argument type "None"  [operator]
pandas/core/arrays/datetimes.py:2544: note: Possible overload variants:
pandas/core/arrays/datetimes.py:2544: note:     def __radd__(self, ndarray[Any, dtype[object_]]) -> ndarray[Any, dtype[object_]]
pandas/core/arrays/datetimes.py:2544: note:     def __radd__(self, BaseOffset) -> BaseOffset
pandas/core/arrays/datetimes.py:2544: note:     def [_DatetimeT <: datetime] __radd__(self, _DatetimeT) -> _DatetimeT
pandas/core/arrays/datetimes.py:2544: note:     def [_TimedeltaT <: timedelta] __radd__(self, _TimedeltaT) -> _TimedeltaT
pandas/core/arrays/datetimes.py:2544: note: Left operand is of type "Optional[Timestamp]"
pandas/core/arrays/datetimes.py:2544: error: Unsupported operand types for - ("None" and "int")  [operator]
pandas/core/arrays/datetimes.py:2544: note: Left operand is of type "Optional[int]"
pandas/core/arrays/datetimes.py:2547: error: Unsupported operand types for - ("None" and "int")  [operator]
pandas/core/arrays/datetimes.py:2547: note: Left operand is of type "Optional[int]"
pandas/core/arrays/datetimes.py:2560: error: "BaseOffset" has no attribute "_apply"  [attr-defined]
pandas/core/arrays/datetimes.py:2574: error: "BaseOffset" has no attribute "_apply"  [attr-defined]
Found 14 errors in 1 file (checked 1398 source files)
``` mypy fixed, just an unrelated timeout remaining Thanks @jbrockmendel 