fix decoding_ind none bug

haoneng.lhn

2023-09-12 eed5cbb9457f0842d9ea8f41cd88459a5dbc9e70

 funasr/models/encoder/abs_encoder.py

@@ -18,4 +18,4 @@
        ilens: torch.Tensor,
        prev_states: torch.Tensor = None,
    ) -> Tuple[torch.Tensor, torch.Tensor, Optional[torch.Tensor]]:
        raise NotImplementedError
        raise NotImplementedError