onnx-simplifier error

[kuroko1t]

Traceback (most recent call last):                                                                                                                                                                                                                         
  File "/root/ghq/github.com/kuroko1t/ghelia/aitrios/convert_ckpt2onnx.py", line 260, in <module>                                                                                                                                                          
    pose_infer.to_onnx()                                                                                                                                                                                                                                   
  File "/root/ghq/github.com/kuroko1t/ghelia/aitrios/convert_ckpt2onnx.py", line 154, in to_onnx                                                                                                                                                           
    nne.cv2onnx(model, input_shape, onnx_file, simplify=True)                                                                                                                                                                                              
  File "/root/.venv/4e05bd248df744710af32da487854159/middle/lib/python3.8/site-packages/nne/convert/onnx.py", line 64, in cv2onnx                                                                                                                          
    model_opt, check_ok = onnx_simplify(onnx_model, input_shape)                                              
  File "/root/.venv/4e05bd248df744710af32da487854159/middle/lib/python3.8/site-packages/nne/convert/common.py", line 38, in onnx_simplify
    model_opt, check_ok = onnxsim.simplify(                                                                                  
  File "/root/.venv/4e05bd248df744710af32da487854159/middle/lib/python3.8/site-packages/onnxsim/onnx_simplifier.py", line 533, in simplify
    assert(isinstance(model, onnx.ModelProto))                                                                               
AssertionError