An issue in data_gen/src/data_io.py for isinstance(field, CenteredGrid)

[321hu]

When I ran the command python gen_ns_incomp.py, I encountered the below error:

File "/home/liyezhang/hzh/PDEBench/pdebench/data_gen/src/data_io.py", line 68, in to_centre_grid
if isinstance(field, CenteredGrid):
TypeError: isinstance() arg 2 must be a type or tuple of types

How I can solve this problem?