load_workbook() raises AttributeError: 'Chartsheet' object has no attribute '_tables'
I'm using v3.0.4 I use this library to process thousands of similarly formatted Excel files. There is one new file that seems to be only different because someone added a chart tab to it. Now when I open it, I get an exception in ``load_workbook()``: ``w = load_workbook(file_path)`` ``Traceback (most recent call last):`` `` File "<console>", line 1, in <module>`` `` File "/Users/mcclure/.local/share/virtualenvs/nextgendesign-b9EAmrED/lib/python3.7/site-packages/openpyxl/reader/excel.py", line 315, in load_workbook`` `` reader.read()`` `` File "/Users/mcclure/.local/share/virtualenvs/nextgendesign-b9EAmrED/lib/python3.7/site-packages/openpyxl/reader/excel.py", line 280, in read`` `` self.read_worksheets()`` `` File "/Users/mcclure/.local/share/virtualenvs/nextgendesign-b9EAmrED/lib/python3.7/site-packages/openpyxl/reader/excel.py", line 251, in read_worksheets`` `` ws.add_table(table)`` `` File "/Users/mcclure/.local/share/virtualenvs/nextgendesign-b9EAmrED/lib/python3.7/site-packages/openpyxl/worksheet/worksheet.py", line 569, in add_table`` `` if self.parent._duplicate_name(table.name):`` `` File "/Users/mcclure/.local/share/virtualenvs/nextgendesign-b9EAmrED/lib/python3.7/site-packages/openpyxl/workbook/workbook.py", line 438, in _duplicate_name`` `` tables = [key.lower() for key in sheet._tables.keys()]`` ``AttributeError: 'Chartsheet' object has no attribute '_tables'`` I noticed that in the 3.0.3 -> 3.0.4 there was a change in ``_tables`` being made available as ``tables`` - might it be as simple as this was missed in Chartsheet? Thanks.
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