AttributeError: 'NoneType' object has no attribute 'strip' when using AzureOpenAI client

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Desribe the bug

BERTopic Error with Content Filtering in AzureOpenAI

Description

When using BERTopic with AzureOpenAI, I'm encountering an error when content filtering is triggered. The error occurs in _openai.py where it tries to strip a None value, failing to properly handle the case where OpenAI returns a content-filtered response.

Error

AttributeError: 'NoneType' object has no attribute 'strip'

Traceback

<bertopic._bertopic.BERTopic object at 0x8cf54a68230>
File "/azureml-envs/azureml_5493e10031d137133cf6acf55ecbab07/lib/python3.12/site-packages/bertopic/representation/_openai.py", line 234, in extract_topics
label = response.choices[0].message.content.strip().replace("topic: ", "")
└ [Choice(finish_reason='content_filter', index=0, logprobs=None, message=ChatCompletionMessage(content=None, refusal=None, rol...
└ ChatCompletion(id='chatcmpl-BTxsrB8nuD2wpjvlGY4BEKxeTXf1K', choices=[Choice(finish_reason='content_filter', index=0, logprobs...
AttributeError: 'NoneType' object has no attribute 'strip'

Suggested Fix

Update the condition to also check if content is not None:

if response and hasattr(response.choices[0].message, "content") and response.choices[0].message.content is not None:
    label = response.choices[0].message.content.strip().replace("topic: ", "")
else:
    label = "No label returned"

Reproduction

BERTopic Version

0.17.0

Start in representation/_openai.py at the failing line in extract_topics, where response.choices[0].message.content is stripped. Inspect the content-filtered response shown in the traceback and handle a missing content value; done means this response no longer raises AttributeError and produces the stated fallback label.