Bug in Weaviate - Update data object instance (Python Client)

Question

I have a Weaviate instance running (ver 1.12.2)

I am playing around with the Python client https://weaviate-python-client.readthedocs.io/en/stable/ (ver 3.4.2) (add - retrieve - delete objects...etc...)

I have come across a weird bug when trying to update a data object.

I am following the example under the update() function at https://weaviate-python-client.readthedocs.io/en/stable/weaviate.data.html

I first add a data object

author_id = client.data_object.create(
    data_object = {'name': 'Philip Pullman', 'age': 64},
    class_name = 'Author'
)

I then retrieve it with client.data_object.get(author_id). This gives me a good output

{'class': 'Author',
 'creationTimeUnix': 1650911164482,
 'id': '00643310-bdd4-47b3-b404-d0aa7c9331f5',
 'lastUpdateTimeUnix': 1650911164482,
 'properties': {'age': 64, 'name': 'Philip Pullman'},
 'vectorWeights': None}

This works fine, but when I try to update the object with :

client.data_object.update(
    data_object = {'age': 74},
    class_name = 'Author',
    uuid = author_id
)

I get the following error:

---------------------------------------------------------------------------
UnexpectedStatusCodeException             Traceback (most recent call last)
<ipython-input-58-84003038f15b> in <module>
----> 1 client.data_object.update(
      2     data_object = {'age': 74},
      3     class_name = 'Author',
      4     uuid = author_id
      5 )

~/anaconda3/envs/tf_gpu_dev/lib/python3.8/site-packages/weaviate/data/crud_data.py in update(self, data_object, class_name, uuid, vector)
    246             # Successful merge
    247             return
--> 248         raise UnexpectedStatusCodeException("Update of the object not successful", response)
    249 
    250     def replace(self,

UnexpectedStatusCodeException: Update of the object not successful! Unexpected status code: 500, with response body: {'error': [{'message': 'repo: merge into index author: shard Iomjx2uCohtc: update vector index: insert doc id 1 to vector index: insert called with nil-vector'}]}

Moreover the annoying thing is that the update has been made in the background !

Running: client.data_object.get(author_id) again, gives the output:

{'class': 'Author',
 'creationTimeUnix': 1650911164482,
 'id': '00643310-bdd4-47b3-b404-d0aa7c9331f5',
 'lastUpdateTimeUnix': 1650911164482,
 'properties': {'age': 74, 'name': 'Philip Pullman'},
 'vectorWeights': None}

The 'age' field has been updated appropriately

Also.... shouldn't lastUpdateTimeUnix also be updated?

Thanks for reading my Q !