Function failure 

pub fn failure(message: &str) -> Action

What: Build the stop action for a wrapper failure described in prose. &str borrows the message; the action owns its formatted copy. Why: These failures (no real Git, a forwarding loop, an unreadable repository) print one prefixed, line-terminated diagnostic on standard error and exit 2.

In TS you’d write (pseudocode):

function failure(message: string): Action;