Fix object merge

lib/utils.js

@@ -361,30 +361,40 @@ function mergeSettings(target, src) {
 
   if (array) {
     target = target || [];
+    // Add items from target into dst
     dst = dst.concat(target);
-    src.forEach(function (e) {
+    // Add non-existent items from source into dst
+    src.forEach(function(e) {
       if (dst.indexOf(e) === -1) {
         dst.push(e);
       }
     });
   } else {
-    if (target && typeof target === 'object') {
-      Object.keys(target).forEach(function (key) {
+    if (target != null && typeof target === 'object') {
+      // Add properties from target to dst
+      Object.keys(target).forEach(function(key) {
         dst[key] = target[key];
       });
     }
-    Object.keys(src).forEach(function (key) {
-      if (typeof src[key] !== 'object' || !src[key]) {
-        dst[key] = src[key];
-      }
-      else {
-        if (!target[key]) {
-          dst[key] = src[key]
+    if (src != null && typeof src === 'object') {
+      // Source is an object
+      Object.keys(src).forEach(function(key) {
+        var srcValue = src[key];
+        if (srcValue == null || typeof srcValue !== 'object') {
+          // The source item value is null, undefined or not an object
+          dst[key] = srcValue;
         } else {
-          dst[key] = mergeSettings(target[key], src[key]);
+          // The source item value is an object
+          if (target == null || typeof target !== 'object' ||
+            target[key] == null) {
+            // If target is not an object or target item value 
+            dst[key] = srcValue;
+          } else {
+            dst[key] = mergeSettings(target[key], src[key]);
+          }
         }
-      }
-    });
+      });
+    }
   }
 
   return dst;