Fix Series.map default for na_action

Author: hamdanal

pandas-stubs/core/series.pyi

@@ -1107,7 +1107,7 @@ class Series(IndexOpsMixin[S1], ElementOpsMixin[S1], NDFrame):
     def map(
         self,
         arg: Callable[[S1], S2 | NAType] | Mapping[S1, S2] | Series[S2],
-        na_action: Literal["ignore"] = ...,
+        na_action: Literal["ignore"],
     ) -> Series[S2]: ...
     @overload
     def map(
@@ -1119,7 +1119,7 @@ class Series(IndexOpsMixin[S1], ElementOpsMixin[S1], NDFrame):
     def map(
         self,
         arg: Callable[[Any], Any] | Mapping[Any, Any] | Series,
-        na_action: Literal["ignore"] | None = ...,
+        na_action: Literal["ignore"] | None = None,
     ) -> Series: ...
     @overload
     def aggregate(

tests/series/test_series.py

@@ -3620,6 +3620,8 @@ def callable(x: int | NAType) -> str | NAType:
     check(
         assert_type(s.map(callable, na_action=None), "pd.Series[str]"), pd.Series, str
     )
+    # na_action defaults to None
+    check(assert_type(s.map(callable), "pd.Series[str]"), pd.Series, str)
 
     series = pd.Series(["a", "b", "c"])
     check(assert_type(s.map(series, na_action=None), "pd.Series[str]"), pd.Series, str)