Cannot send meta=None in from_json to flask-wtf>=0.14#47

The classmethod from_json has default meta=None, which fails at https://github.com/lepture/flask-wtf/blob/master/flask_wtf/form.py#L85 as that assumes meta is a dict if present: File "/usr/local/lib/python2.7/dist-packages/wtforms_json/__init__.py", line 233, in from_json **kwargs File "/usr/local/lib/python2.7/dist-packages/wtforms/form.py", line 212, in __call__ return type.__call__(cls, *args, **kwargs) File "/usr/local/lib/python2.7/dist-packages/flask_wtf/form.py", line 85, in __init__ kwargs.setdefault('meta', {}).setdefault('csrf', csrf_enabled) AttributeError: 'NoneType' object has no attribute 'setdefault'