Build documentation failed with key error

Hello, everyone.
I’d like to build an offline-document with pdf.
When I make the doc, an error KeyError: 'CELU'occurs on building the activation images.

Then I comment the CELU line in the, it succeeds in making the tex file.

when I compile the tex file to generate pdf, errors occur again. It takes me a lot of time to find out. It’s because the command like this \text{window_length} . But when I check the docstring in the source file, it’s \text{window\_length}. So how can I make the right tex file.