fn require(tool: &str) -> Result<(), String>Expand description
Fail, naming the tool, when tool is not usable.
Neither tool ships with cargo, so a missing one reaches the step as a bare “No such file or directory” under a name that says what the step wanted; this reports which tool is absent instead. How to install it is left to the contributor: both are distributed outside cargo, so a command named here would be a guess.