diff --git a/lib/chrome.js b/lib/chrome.js
index de85c42..0c2e6e8 100644
--- a/lib/chrome.js
+++ b/lib/chrome.js
@@ -422,13 +422,13 @@ var ChromeObject = function() {
     };
 
     this.sendPageRPC = function(method, params) {
-        var result = null;
+        var response = null;
 
         try {
             if (this.pageId != "") {
                 var url = "http://localhost:3000/devtools/page/" + this.pageId + "?port=" + this.debuggingPort;
                 try {
-                    result = HTTP.create()
+                    response = HTTP.create()
                         .setContentType("application/json")
                         .setDataType("json")
                         .open("POST", url)
@@ -440,9 +440,18 @@ var ChromeObject = function() {
                         .send()
                         .responseBody
                     ;
+                    
+                    // response if error
+                    if ("result" in response) {
+                        (function(r) {
+                            if ("subtype" in r && r.subtype == "error") {
+                                console.warn("[WebBrowser]", r.description);
+                            }
+                        })(response.result.result);
+                    }
                 } catch (e) {
                     console.warn(e.message);
-                    result = {};
+                    response = {};
                 }
                 
                 pageEventId.set(pageEventId.get() + 1);
@@ -450,7 +459,7 @@ var ChromeObject = function() {
             } else {
                 this.setPageId(null);
                 if (this.pageId != "") {
-                    result = this.sendPageRPC(method, params);
+                    response = this.sendPageRPC(method, params);
                 } else {
                     console.error("Page not found");
                 }
@@ -459,7 +468,7 @@ var ChromeObject = function() {
             console.log("ChromeObject.sendPageRPC() ->", e.message);
         }
 
-        return result;
+        return response;
     };
 
     this.navigate = function(url) {
@@ -495,7 +504,9 @@ var ChromeObject = function() {
     this.getEvaluatedValue = function(expression) {
         try {
             var response = this.evaluate(expression);
-            return response.result.result.value;
+            return (function(r) {
+                return ("value" in r ? r.value : "");
+            })(response.result.result);
         } catch (e) {
             console.error("ChromeObject.getEvaluatedValue() ->", e.message);
             return "";
@@ -1493,7 +1504,7 @@ exports.startDebugInPrivate = function(url, proxy, profileName, debuggingPort, i
 
 exports.publisherName = publisherName;
 
-exports.VERSIONINFO = "Chrome Web Browser Debugging Interface (chrome.js) version 0.5";
+exports.VERSIONINFO = "Chrome Web Browser Debugging Interface (chrome.js) version 0.5.1";
 exports.AUTHOR = "gnh1201@catswords.re.kr";
 exports.global = global;
 exports.require = global.require;