UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36

Steps to reproduce the problem:
1. Loading the extension to chrome webstore
2. running the extension
3. 

What is the expected behavior?
Extension should be running as it is running in developer mode

What went wrong?
This extension may have been corrupted

Did this work before? N/A 

Chrome version: 67.0.3396.99  Channel: n/a
OS Version: 10.0
Flash Version: 

I developing Devtools extension by following this example from github. I am able to run the extension fine in the developer mode but when i moved the same to web store. I am facing the following issue This extension may have been corrupted. and found following console error :

(Uncaught TypeError: Cannot read property 'connect' of undefined
    at createChannel (messaging.js:13)

messaging.js:13 has this code 

(function createChannel() {   
    var port = chrome.extension.connect({
        name: "Sample" 
    });
    var count=0;
    var activeTabClass;
    // Listen to messages from the background page
    port.onMessage.addListener(function (message) {
		setTimeout(function(){showResult(message);},1)       

    });

and Manifest.json has this.

{
  "name": "Sample Engine",
  "version": "1.04",
  "manifest_version": 2,
  "devtools_page": "devtools.html",
  "description": "Chrome Developer Tools",
  "icons": { "64": "images/pact.png" },
  "background": {
    "scripts": [
      "scripts/jquery1.12.4-min.js",
      "scripts/jquery-ui.min.js",
     "scripts/background.js",
	  "scripts/panel.js",
	  "scripts/tab-order.js",
	  "scripts/high-lighter.js"	  
    ],
	   "persistent": false
  },
  "content_scripts": [
    {     
      "js": [ "scripts/jquery1.12.4-min.js", "scripts/jquery-ui.min.js"],
	  "css": ["css/Injected-styles.css"]
    }
  ],

  "permissions": [
    "activeTab",
    "tabs",	
    "http://*/*",
    "https://*/*",
	"storage"  
  ]
}