fix: check existence of variable res before iteration

[ahmetmeleq]

Handles a case where Paddle returns a list item in ocr_data as None in partition.

• While parsing PaddleOCR data, it was assumed that PaddleOCR does not return None for any list item in ocr_data.
• Removed the assumption by skipping the text region whenever this happens.

[cragwolfe]

is there an existing GH issue for this, and/or a file where this causes the error?

[ahmetmeleq]

@cragwolfe

This PR addresses a community response thread where it was not possible for the user to share their file; so we don't know why exactly PaddleOCR returns that portion of ocr_data as None (which causes the error, see the copied stack trace):

https://unstructuredw-kbe4326.slack.com/archives/C044N0YV08G/p1699891467623009

However by reading through I saw that we were assuming that PaddleOCR does not return None for any list item in ocr_data.

I've removed that assumption here, addressing the case by skipping the text region when this happens (similar to how we handle another case here).

Copied stack trace:

Error in partitioning content: 'NoneType' object is not iterable
Traceback (most recent call last):
  File "/home/notebook-user/unstructured/ingest/error.py", line 19, in wrapper
    return f(*args, **kwargs)
  File "/home/notebook-user/unstructured/ingest/interfaces.py", line 438, in partition_file
    elements = partition(
  File "/home/notebook-user/unstructured/partition/auto.py", line 383, in partition
    elements = _partition_pdf(
  File "/home/notebook-user/unstructured/documents/elements.py", line 371, in wrapper
    elements = func(*args, **kwargs)
  File "/home/notebook-user/unstructured/file_utils/filetype.py", line 591, in wrapper
    elements = func(*args, **kwargs)
  File "/home/notebook-user/unstructured/file_utils/filetype.py", line 546, in wrapper
    elements = func(*args, **kwargs)
  File "/home/notebook-user/unstructured/chunking/title.py", line 297, in wrapper
    elements = func(*args, **kwargs)
  File "/home/notebook-user/unstructured/partition/pdf.py", line 182, in partition_pdf
    return partition_pdf_or_image(
  File "/home/notebook-user/unstructured/partition/pdf.py", line 339, in partition_pdf_or_image
    _layout_elements = _partition_pdf_or_image_with_ocr(
  File "/home/notebook-user/unstructured/utils.py", line 179, in wrapper
    return func(*args, **kwargs)
  File "/home/notebook-user/unstructured/partition/pdf.py", line 769, in _partition_pdf_or_image_with_ocr
    page_elements = _partition_pdf_or_image_with_ocr_from_image(
  File "/home/notebook-user/unstructured/partition/pdf.py", line 800, in _partition_pdf_or_image_with_ocr_from_image
    ocr_data = get_layout_elements_from_ocr(
  File "/home/notebook-user/unstructured/partition/ocr.py", line 359, in get_layout_elements_from_ocr
    ocr_regions = get_ocr_layout_from_image(
  File "/home/notebook-user/unstructured/partition/ocr.py", line 462, in get_ocr_layout_from_image
    ocr_regions = get_ocr_layout_paddle(image)
  File "/home/notebook-user/unstructured/partition/ocr.py", line 521, in get_ocr_layout_paddle
    ocr_regions = parse_ocr_data_paddle(ocr_data)
  File "/home/notebook-user/unstructured/partition/ocr.py", line 601, in parse_ocr_data_paddle
    for line in res:
TypeError: 'NoneType' object is not iterable
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
  File "/home/notebook-user/unstructured/ingest/pipeline/partition.py", line 48, in run
    elements = doc.process_file(
  File "/home/notebook-user/unstructured/ingest/interfaces.py", line 479, in process_file
    isd_elems_raw = self.partition_file(partition_config=partition_config, **partition_kwargs)
  File "/home/notebook-user/unstructured/ingest/error.py", line 22, in wrapper
    raise cls(cls.error_string.format(str(error))) from error
unstructured.ingest.error.PartitionError: Error in partitioning content: 'NoneType' object is not iterable

[yuming-long]

LGTM!