Merge pull request #22007 from [release-2.40.0] Fix FlatMap numpy array bug

[release-2.40.0] Fix FlatMap numpy array bug

Author: pabloem

sdks/python/apache_beam/runners/common.py

@@ -1561,7 +1561,8 @@ def handle_process_outputs(
     A value wrapped in a TaggedOutput object will be unwrapped and
     then dispatched to the appropriate indexed output.
     """
-    results = results or []
+    if results is None:
+      results = []
 
     # TODO(https://github.com/apache/beam/issues/20404): Verify that the
     #  results object is a valid iterable type if
@@ -1614,7 +1615,9 @@ def handle_process_batch_outputs(
     A value wrapped in a TaggedOutput object will be unwrapped and
     then dispatched to the appropriate indexed output.
     """
-    results = results or []
+    if results is None:
+      results = []
+
     output_element_count = 0
     for result in results:
       tag, result = self._handle_tagged_output(result)

sdks/python/apache_beam/runners/portability/fn_api_runner/fn_runner_test.py

@@ -454,6 +454,15 @@ def test_pardo_side_input_dependencies(self):
                 ExpectingSideInputsFn(f'Do{k}'),
                 *[beam.pvalue.AsList(inputs[s]) for s in range(1, k)]))
 
+  def test_flatmap_numpy_array(self):
+    with self.create_pipeline() as p:
+      pc = (
+          p
+          | beam.Create([np.array(range(10))])
+          | beam.FlatMap(lambda arr: arr))
+
+      assert_that(pc, equal_to([np.int64(i) for i in range(10)]))
+
   @unittest.skip('https://github.com/apache/beam/issues/21228')
   def test_pardo_side_input_sparse_dependencies(self):
     with self.create_pipeline() as p: