REGR: Series.mode with boolean and pd.NA (#42131)

Author: jbrockmendel

pandas/core/algorithms.py

@@ -140,7 +140,11 @@ def _ensure_data(values: ArrayLike) -> tuple[np.ndarray, DtypeObj]:
             return np.asarray(values).view("uint8"), values.dtype
         else:
             # i.e. all-bool Categorical, BooleanArray
-            return np.asarray(values).astype("uint8", copy=False), values.dtype
+            try:
+                return np.asarray(values).astype("uint8", copy=False), values.dtype
+            except TypeError:
+                # GH#42107 we have pd.NAs present
+                return np.asarray(values), values.dtype
 
     elif is_integer_dtype(values.dtype):
         return np.asarray(values), values.dtype

pandas/tests/reductions/test_reductions.py

@@ -1480,3 +1480,10 @@ def test_mode_sortwarning(self):
             result = result.sort_values().reset_index(drop=True)
 
         tm.assert_series_equal(result, expected)
+
+    def test_mode_boolean_with_na(self):
+        # GH#42107
+        ser = Series([True, False, True, pd.NA], dtype="boolean")
+        result = ser.mode()
+        expected = Series({0: True}, dtype="boolean")
+        tm.assert_series_equal(result, expected)