BUG: Series.get() with ExtensionArray and integer index

doc/source/whatsnew/v0.23.1.txt

@@ -81,6 +81,7 @@ Indexing
 - Bug in :meth:`Series.reset_index` where appropriate error was not raised with an invalid level name (:issue:`20925`)
 - Bug in :func:`interval_range` when ``start``/``periods`` or ``end``/``periods`` are specified with float ``start`` or ``end`` (:issue:`21161`)
 - Bug in :meth:`MultiIndex.set_names` where error raised for a ``MultiIndex`` with ``nlevels == 1`` (:issue:`21149`)
+- Bug in :meth:`Series.get` for ``Series`` using ``ExtensionArray`` and integer index (:issue:`21257`)
 -
 
 I/O

pandas/core/indexes/base.py

@@ -2972,16 +2972,20 @@ def get_value(self, series, key):
         # use this, e.g. DatetimeIndex
         s = getattr(series, '_values', None)
         if isinstance(s, (ExtensionArray, Index)) and is_scalar(key):
-            # GH 20825
+            # GH 20882, 21257
             # Unify Index and ExtensionArray treatment
             # First try to convert the key to a location
-            # If that fails, see if key is an integer, and
+            # If that fails, raise a KeyError if an integer
+            # index, otherwise, see if key is an integer, and
             # try that
             try:
                 iloc = self.get_loc(key)
                 return s[iloc]
             except KeyError:
-                if is_integer(key):
+                if (len(self) > 0 and
+                        self.inferred_type in ['integer', 'boolean']):
+                    raise
+                elif is_integer(key):
                     return s[key]
 
         s = com._values_from_object(series)

pandas/tests/extension/base/getitem.py

@@ -130,7 +130,7 @@ def test_get(self, data):
         expected = s.iloc[[0, 1]]
         self.assert_series_equal(result, expected)
 
-        assert s.get(-1) == s.iloc[-1]
+        assert s.get(-1) is None
         assert s.get(s.index.max() + 1) is None
 
         s = pd.Series(data[:6], index=list('abcdef'))
@@ -147,6 +147,11 @@ def test_get(self, data):
         assert s.get(-1) == s.iloc[-1]
         assert s.get(len(s)) is None
 
+        # GH 21257
+        s = pd.Series(data)
+        s2 = s[::2]
+        assert s2.get(1) is None
+
     def test_take_sequence(self, data):
         result = pd.Series(data)[[0, 1, 3]]
         assert result.iloc[0] == data[0]