ChromaDocumentStore search raise error when document has no metadata

[Guest400123064]

Describe the bug
In ChromaDocumentStore._query_result_to_documents method, line 375, the method tries to convert from chromadb metadatas to Haystack document metadata. It checks if the returned result has any metadata by result.get("metadatas"). This does not actually check if there is any metadata because the returned value will be a nested list, which is always not None. Then on line 376, if the metadata is actually empty, the second subscription will break.

To Reproduce
Simply create a document store with no-metadata documents and try to call ChromaDocumentStore.search(["test query text"], 1). Commenting out the code snippet mentioned above should avoid error (but no metadata in returned documents)

Describe your environment (please complete the following information):

• OS: MacOS
• Haystack version: 2.0.1
• Integration version: N/A, but as of April 16th 2024, the code on main branch is still causing the reported problem; should be tagged chroma-v0.15.0

[anakin87]

related to #462 (maybe a dupicate)

[Guest400123064]

Got it, yea, I think this is indeed a duplicate

[anakin87]

Closing as it is a duplicate.