BUG: fix Series(extension array) + extension array values addition

doc/source/whatsnew/v0.24.0.txt

@@ -493,6 +493,7 @@ ExtensionType Changes
 - :meth:`Series.combine()` with scalar argument now works for any function type (:issue:`21248`)
 - :meth:`Series.astype` and :meth:`DataFrame.astype` now dispatch to :meth:`ExtensionArray.astype` (:issue:`21185:`).
 - Added :meth:`pandas.api.types.register_extension_dtype` to register an extension type with pandas (:issue:`22664`)
+- Bug in :meth:`pandas.core.ops.dispatch_to_extension_op` where addition of ``Series`` of ``IntegerArray`` and ``IntegerArray`` values raise runtime exception (:issue `22478`)
 
 .. _whatsnew_0240.api.incompatibilities:
 

pandas/core/ops.py

@@ -1182,7 +1182,7 @@ def dispatch_to_extension_op(op, left, right):
                 new_right = [new_right]
             new_right = list(new_right)
         elif is_extension_array_dtype(right) and type(left) != type(right):
-            new_right = list(new_right)
+            new_right = list(right)
         else:
             new_right = right
 

pandas/tests/arrays/test_integer.py

@@ -587,6 +587,14 @@ def test_cross_type_arithmetic():
     tm.assert_series_equal(result, expected)
 
 
+def test_arith_extension_array_values():
+    # GH 22478
+    s = pd.Series([1, 2, 3], dtype='Int64')
+    result = s + s.values
+    expected = pd.Series([2, 4, 6], dtype='Int64')
+    tm.assert_series_equal(result, expected)
+
+
 def test_groupby_mean_included():
     df = pd.DataFrame({
         "A": ['a', 'b', 'b'],