make sure that process exits ok

ts/npmci.bash.ts

@@ -1,9 +1,12 @@
 import "typings-global";
 import * as plugins from "./npmci.plugins";
 export let bash = (commandArg) => {
-    plugins.shelljs.exec(
+    let exitCode = plugins.shelljs.exec(
         "bash -c \"source /usr/local/nvm/nvm.sh &&" +
         commandArg +
         "\""
-    );
+    ).code;
+    if(exitCode !== 0){
+        process.exit(1);
+    }
 }