Unassigned variables cause UnboundLocalError in Kotoba

Affected Version: Yotsuba 3.0 / Kotoba 2.0

Description:

File "/Users/jnopporn/Code/www-v11/yotsuba/lib/kotoba.py", line 253, in data max_depth = 'max_depth' in kwargs and (base.isNaturalNumber(max_depth) and max_depth - 1 or None) or None UnboundLocalError: local variable 'max_depth' referenced before assignment

Reproductive Steps: Attempt to call DOMElement.data()

Solution (Proposal): From

    max_depth = 'max_depth' in kwargs and (base.isNaturalNumber(max_depth) and max_depth - 1 or None) or None

to

    max_depth = None
    if 'max_depth' in kwargs and base.isNaturalNumber(max_depth):
        max_depth = max_depth - 1