Change the target length and raise an issue

[Wietc]

When I tried to generate midi longer and I change the parameter target_seq_length[in argument_funcs.py] to 4096(default 1024), the issues can be reproduced:
RuntimeError: The size of tensor a (2049) must match the size of tensor b (2048) at non-singleton dimension 0

I want to know it is the Transformer's limit or just the MusicTransformer settings cause the problem?