Error occurs when not supplying data

[BruceChen2017]

(ggplot() + 
        geom_bar(aes(np.array([1,1,2]))))

will cause error

D:\Python36\lib\site-packages\plotnine\layer.py in generate_data(self, plot_data)
    240             try:
--> 241                 self.data = plot_data.copy()
    242             except AttributeError:

AttributeError: 'NoneType' object has no attribute 'copy'  

But it works under r with

ggplot() + 
        geom_bar(aes(c(1,1,2)))