darwin.linux-builder: Exit scripts on error

For example, if the user decided to ctrl-c upon getting the sudo
password prompt, the script previously continued on to start the VM, but
that should not be the case.

nixos/modules/profiles/macos-builder.nix

@@ -145,6 +145,8 @@ in
         # This installCredentials script is written so that it's as easy as
         # possible for a user to audit before confirming the `sudo`
         installCredentials = hostPkgs.writeShellScript "install-credentials" ''
+          set -euo pipefail
+
           KEYS="''${1}"
           INSTALL=${hostPkgs.coreutils}/bin/install
           "''${INSTALL}" -g nixbld -m 600 "''${KEYS}/${user}_${keyType}" ${privateKey}
@@ -154,6 +156,9 @@ in
         hostPkgs = config.virtualisation.host.pkgs;
 
         script = hostPkgs.writeShellScriptBin "create-builder" (
+          ''
+            set -euo pipefail
+          '' +
           # When running as non-interactively as part of a DarwinConfiguration the working directory
           # must be set to a writeable directory.
         (if cfg.workingDirectory != "." then ''