$_
nvm.sh
nvm.sh uses `NVM_SCRIPT_SOURCE="$_"` to detect its source location. Adding `: nvm.sh` before each source line ensures `$_` is set correctly, preventing breakage when the previous command (e.g., `set -ex`) overwrites it.
nvm use
nvm install
--save
Fixes #2849. Co-authored-by: Martin <maartin00000@gmail.com> Co-authored-by: Jordan Harband <ljharb@gmail.com>