Erro when specifying "null" entities in stories

[humcasma]

Rasa version: 2.4.2

Rasa SDK version 2.4.1

Python version: 3.7.10

Operating system (windows, osx, ...): Linux-4.19.112+-x86_64-with-Ubuntu-18.04-bionic

Issue:
Rasa crashes when a story contains a "null" entity. That story would be used to handle the case where an intent is identified but an expected entity is not provided.

- story: test
  steps:
  - intent: test_intent
    entities:
    - test_entity: null
  - action: test_action

Error (including full traceback):

 File "/content/rasa/bin/rasa", line 8, in <module>
    sys.exit(main())
  File "/content/rasa/lib/python3.7/site-packages/rasa/__main__.py", line 116, in main
    cmdline_arguments.func(cmdline_arguments)
  File "/content/rasa/lib/python3.7/site-packages/rasa/cli/train.py", line 58, in <lambda>
    train_parser.set_defaults(func=lambda args: train(args, can_exit=True))
  File "/content/rasa/lib/python3.7/site-packages/rasa/cli/train.py", line 102, in train
    finetuning_epoch_fraction=args.epoch_fraction,
  File "/content/rasa/lib/python3.7/site-packages/rasa/train.py", line 109, in train
    loop,
  File "/content/rasa/lib/python3.7/site-packages/rasa/utils/common.py", line 307, in run_in_loop
    result = loop.run_until_complete(f)
  File "uvloop/loop.pyx", line 1456, in uvloop.loop.Loop.run_until_complete
  File "/content/rasa/lib/python3.7/site-packages/rasa/train.py", line 174, in train_async
    finetuning_epoch_fraction=finetuning_epoch_fraction,
  File "/content/rasa/lib/python3.7/site-packages/rasa/train.py", line 271, in _train_async_internal
    new_fingerprint = await model.model_fingerprint(file_importer)
  File "/content/rasa/lib/python3.7/site-packages/rasa/model.py", line 343, in model_fingerprint
    FINGERPRINT_STORIES_KEY: stories.fingerprint(),
  File "/content/rasa/lib/python3.7/site-packages/rasa/shared/core/training_data/structures.py", line 414, in fingerprint
    stories_as_yaml = YAMLStoryWriter().stories_to_yaml(self.story_steps)
  File "/content/rasa/lib/python3.7/site-packages/rasa/shared/core/training_data/story_writer/yaml_story_writer.py", line 119, in stories_to_yaml
    stories.append(self.process_story_step(story_step))
  File "/content/rasa/lib/python3.7/site-packages/rasa/shared/core/training_data/story_writer/yaml_story_writer.py", line 149, in process_story_step
    processed = self.process_event(event)
  File "/content/rasa/lib/python3.7/site-packages/rasa/shared/core/training_data/story_writer/yaml_story_writer.py", line 163, in process_event
    return self.process_user_utterance(event, self._is_test_story)
  File "/content/rasa/lib/python3.7/site-packages/rasa/shared/core/training_data/story_writer/yaml_story_writer.py", line 230, in process_user_utterance
    if entity["value"]:
KeyError: 'value'

Command or request that led to error:

rasa train

[sara-tagger]

Thanks for the issue, @dakshvar22 will get back to you about it soon!

You may find help in the docs and the forum, too 🤗