If you supersample a concatenated Clip you get the following error:

File "/usr/local/lib/python3.5/dist-packages/moviepy/video/fx/supersample.py", line 12, in supersample
return clip.fl(fl)
File "/usr/local/lib/python3.5/dist-packages/moviepy/Clip.py", line 136, in fl
newclip = self.set_make_frame(lambda t: fun(self.get_frame, t))
File "", line 2, in set_make_frame
File "/usr/local/lib/python3.5/dist-packages/moviepy/decorators.py", line 14, in outplace
f(newclip, a, **k)
File "/usr/local/lib/python3.5/dist-packages/moviepy/video/VideoClip.py", line 694, in set_make_frame
self.size = self.get_frame(0).shape[:2][::-1]
File "", line 2, in get_frame
File "/usr/local/lib/python3.5/dist-packages/moviepy/decorators.py", line 89, in wrapper
return f(new_a, **new_kw)
File "/usr/local/lib/python3.5/dist-packages/moviepy/Clip.py", line 95, in get_frame
return self.make_frame(t)
File "/usr/local/lib/python3.5/dist-packages/moviepy/Clip.py", line 136, in
newclip = self.set_make_frame(lambda t: fun(self.get_frame, t))
File "/usr/local/lib/python3.5/dist-packages/moviepy/video/fx/supersample.py", line 9, in fl
avg = np.mean(1.0np.array([gf(t_) for t_ in tt], dtype='uint16'), axis=0)
File "/usr/local/lib/python3.5/dist-packages/moviepy/video/fx/supersample.py", line 9, in
avg = np.mean(1.0np.array([gf(t_) for t_ in tt], dtype='uint16'), axis=0)
File "", line 2, in get_frame
File "/usr/local/lib/python3.5/dist-packages/moviepy/decorators.py", line 89, in wrapper
return f(*new_a, **new_kw)
File "/usr/local/lib/python3.5/dist-packages/moviepy/Clip.py", line 95, in get_frame
return self.make_frame(t)
File "/usr/local/lib/python3.5/dist-packages/moviepy/video/compositing/concatenate.py", line 82, in make_frame
i = max([i for i, e in enumerate(tt) if e <= t])
ValueError: max() arg is an empty sequence

Example code:

from moviepy.editor import concatenate_videoclips
from moviepy.video.fx.all import supersample

def supersample_error(inputclip):
    return supersample(concatenate_videoclips([inputclip, inputclip]), 1, 1)