diff --git a/index.js b/index.js
index 8251471..a56a99c 100644
--- a/index.js
+++ b/index.js
@@ -322,7 +322,9 @@
      */
     function argJSONEncode(args) {
         each(args, function (arg, i) {
-            args[i] = JSON.stringify(arg);
+            if (typeof arg === 'object') {
+                args[i] = JSON.stringify(arg);
+            }
         });
 
         return args;
@@ -993,6 +995,10 @@
                     processName = processName.slice(0, dotIndex);
                 }
 
+                if (!processorCreators[processName] || typeof processorCreators[processName] !== 'function') {
+                    throw new Error('[' + apiContainer.options.errorTitle + '] processName: ' + processName + ' is not a function');
+                }
+
                 var processor = processorCreators[processName](description, option, apiContainer);
                 if (typeof processor === 'function') {
                     processors.push(processor);