Plot rendering error: object of type 'NoneType' has no len(); metadata = {'Entries': 152030, 'Name': 'TimePerFitDist-0', 'Overflow': 1554.0, 'Type': 'Histo1d', 'Underflow': 0.0, 'x': {'AxisTitle': 'Fit Time [us]', 'Bins': 201, 'High': 401.0, 'Low': -1.0}, 'y': {'AxisTitle': 'Number of Pixels'}, 'z': {'AxisTitle': 'z'}}