Throw error for Option to option() or requiredOption() (#1655)

* Throw error for wrong argument to option or requiredOption

* Make test and error message more specific

Author: shadowspawn

lib/command.js

@@ -580,6 +580,9 @@ Expecting one of '${allowedValues.join("', '")}'`);
    * @api private
    */
   _optionEx(config, flags, description, fn, defaultValue) {
+    if (typeof flags === 'object' && flags instanceof Option) {
+      throw new Error('To add an Option object use addOption() instead of option() or requiredOption()');
+    }
     const option = this.createOption(flags, description);
     option.makeOptionMandatory(!!config.mandatory);
     if (typeof fn === 'function') {