Changes while checking the intent mapping & new test

- Replaced try/except statement with if/else when checking if intent mapping is empty.
- Minor rewording on the exception message.
- Added a new test to check if the exception is correctly raised.

rasa/shared/core/domain.py

@@ -327,14 +327,14 @@ def _transform_intent_properties_for_internal_use(
         """
         name, properties = list(intent.items())[0]
 
-        try:
+        if properties:
             properties.setdefault(USE_ENTITIES_KEY, True)
-        except:
+        else:
             raise InvalidDomain(
                 f"In the `domain.yml` file, the intent `{name}` cannot have value of"
                 f" `{type(properties)}`. This can happen if you add an intent with the"
-                f"`:`(colon character) after it and do not add any further information"
-                f"to this specific intent."
+                f" `:` (colon character) after it and do not add any"
+                f" further information to this specific intent."
                 f" If you remove the `:` character it should work. Please see "
                 f"{rasa.shared.constants.DOCS_URL_DOMAINS} for more information on how"
                 f" to correctly add `intents` in the `domain` and"

tests/shared/core/test_domain.py

@@ -1306,3 +1306,13 @@ def test_is_valid_domain_doesnt_raise_with_invalid_yaml(tmpdir: Path):
         potential_domain_path,
     )
     assert not Domain.is_domain_file(potential_domain_path)
+
+
+def test_domain_with_empty_intent_mapping():
+    # domain.yml with intent (intent_name) that has a `:` character
+    # and nothing after it.
+    test_yaml = """intents:
+    - intent_name:"""
+
+    with pytest.raises(InvalidDomain):
+        Domain.from_yaml(test_yaml).as_dict()