Fix missing ref on globalOptions in mergeOptions() (#3281)

lib/util.js

@@ -1295,7 +1295,7 @@ exports.mergeOptions = function (mergeTarget, options, option, allowDeletion = f
       }
       else {
         if (options[option].enabled === undefined) {
-          if (globalOptions[option].enabled !== undefined) {
+          if (globalOptions[option] !== undefined  && globalOptions[option].enabled !== undefined) {
             mergeTarget[option].enabled = globalOptions[option].enabled;
           } else {
             // assume this is the correct value