error when trying to perform "mdbook build"

[man-chi]

I have just tried to install and build from the latest version but encounted an error, any idea? thanks in advance

$ mdbook build
2022-05-27 00:52:15 [INFO] (mdbook::book): Book building has started ^[[Athread 'main' panicked at 'called Option::unwrap() on a None value', src/lib.rs:106:83 note: run with RUST_BACKTRACE=1 environment variable to display a backtrace 2022-05-27 00:52:16 [ERROR] (mdbook::utils): Error: The "katex" preprocessor exited unsuccessfully with exit status: 101 status