commandHandler does not check _ as command.

lib/readline-sync.js

@@ -1042,7 +1042,7 @@ function getClHandler(commandHandler, options) {
       cmdKey = clHandler.args[0] || '';
       if (!options.caseSensitive) { cmdKey = cmdKey.toLowerCase(); }
       clHandler.hRes =
-        hIndex.hasOwnProperty(cmdKey) ?
+        cmdKey !== '_' && hIndex.hasOwnProperty(cmdKey) ?
           hIndex[cmdKey].apply(res, clHandler.args.slice(1)) :
         hIndex.hasOwnProperty('_') ? hIndex._.apply(res, clHandler.args) : null;
       return {res: res, forceNext: false};

package.json

@@ -1,6 +1,6 @@
 {
   "name": "readline-sync",
-  "version": "1.2.18",
+  "version": "1.2.19",
   "title": "readlineSync",
   "description": "Synchronous Readline for interactively running to have a conversation with the user via a console(TTY).",
   "keywords": [