rustic-setup-doc error

[mbsmith]

When running this command I get:

rustic-doc-convert.sh: line 34: cd: .rustup/toolchains//share/doc/rust/html/std: No such file or director

The sed line in that script looks for a rust toolchain with (default) but does not manage to find
a valid toolchain if it has more than default on that line.

For instance:
stable-aarch64-apple-darwin (active, default)

The attempt to extract the default toolchain with the following doesn't work. :
rustup show | sed -nr 's/(.*) \(default\)/\1/p'