Handle invalid styles gracefully
Created originally on Bitbucket by hedgeddown (Brett Haydon)
When opening an existing .xlsx (that was converted from an xls) I get an error when the styles are being bound to the workbook.
openpyxl/reader/excel.py", line 221, in load_workbook
apply_stylesheet(archive, wb) # bind styles to workbook
Specifically in this instance it appears to be something to do with the font.
openpyxl/descriptors/base.py", line 89, in __set__
raise ValueError('Max value is {0}'.format(self.max))
ValueError: Max value is 14
Since I don't want to retain the style - I just want to access the data without having to manually remove the style it would be nice to ignore the existing styles rather than apply_stylesheet, but otherwise it would be nice to ignore value errors that are coming from the file itself.