Services (small_pr)(fix): Added missing return on data template error (#12184)

* Added return on data template error

* Rebased so not sure why spelling errors returned...

tests/helpers/test_service.py

@@ -68,6 +68,24 @@ class TestServiceHelpers(unittest.TestCase):
 
         self.assertEqual('goodbye', self.calls[0].data['hello'])
 
+    def test_bad_template(self):
+        """Test passing bad template."""
+        config = {
+            'service_template': '{{ var_service }}',
+            'entity_id': 'hello.world',
+            'data_template': {
+                'hello': '{{ states + unknown_var }}'
+            }
+        }
+
+        service.call_from_config(self.hass, config, variables={
+            'var_service': 'test_domain.test_service',
+            'var_data': 'goodbye',
+        })
+        self.hass.block_till_done()
+
+        self.assertEqual(len(self.calls), 0)
+
     def test_split_entity_string(self):
         """Test splitting of entity string."""
         service.call_from_config(self.hass, {