BUG: Fix Index.get_level_values() mishandling of boolean, pd.NA, np.nan, and pd.NaT levels

pandas/_libs/__init__.py

@@ -1,4 +1,5 @@
 __all__ = [
+    "NA",
     "Interval",
     "NaT",
     "NaTType",
@@ -16,6 +17,7 @@
 import pandas._libs.pandas_parser  # isort: skip # type: ignore[reportUnusedImport]
 import pandas._libs.pandas_datetime  # noqa: F401 # isort: skip # type: ignore[reportUnusedImport]
 from pandas._libs.interval import Interval
+from pandas._libs.missing import NA
 from pandas._libs.tslibs import (
     NaT,
     NaTType,

pandas/core/indexes/base.py

@@ -2084,7 +2084,24 @@ def _validate_index_level(self, level) -> None:
         verification must be done like in MultiIndex.
 
         """
-        if isinstance(level, int):
+        # Explicitly raise for missing/null values to match pandas convention
+        # Also reject all NA-like values (np.nan, pd.NA, pd.NaT, etc.)
+        if isna(level):
+            raise KeyError(
+                f"Requested level ({level}) does not match index name ({self.name})"
+            )
+
+        # Reject booleans unless the index name is actually a boolean and matches
+        if isinstance(level, bool):
+            if level != self.name:
+                raise KeyError(
+                    f"Requested level ({level}) does not match index name ({self.name})"
+                )
+            return
+
+        # Integer-like levels
+        if lib.is_integer(level):
+            # Exclude bools (already handled above)
             if level < 0 and level != -1:
                 raise IndexError(
                     "Too many levels: Index has only 1 level, "
@@ -2094,7 +2111,11 @@ def _validate_index_level(self, level) -> None:
                 raise IndexError(
                     f"Too many levels: Index has only 1 level, not {level + 1}"
                 )
-        elif level != self.name:
+            return
+
+        # For all other types, require exact match to index name
+        # Use pandas' isna for both level and self.name to catch NA-like names
+        if isna(self.name) or level != self.name:
             raise KeyError(
                 f"Requested level ({level}) does not match index name ({self.name})"
             )