refactor: set null string '' as the null value of user token

test/home.html

@@ -200,7 +200,8 @@ header("Allow: GET, POST, OPTIONS, PUT, DELETE");
         var PROJECTLIST = []
 
         window.onload = async function() {
-            await getUserTokenFromVscode()
+            await getUserTokenFromVSCode()
+
             if (USERTOKEN) {
                 loadPageModules()
             } else {
@@ -213,11 +214,11 @@ header("Allow: GET, POST, OPTIONS, PUT, DELETE");
             // loadProjects()
         }
 
-        async function getUserTokenFromVscode() {
+        async function getUserTokenFromVSCode() {
             await communicateVSCodeByWebview('getUserToken', null)
             .then(async data => {
                 const userToken = data.userToken
-                if (userToken === 'none') {
+                if (userToken === '') {
                     // do nothing
                 } else {
                     // verify user token
@@ -231,9 +232,9 @@ header("Allow: GET, POST, OPTIONS, PUT, DELETE");
                 }
 
             })
-            .catch(error => [
-                console.log('Failed to get user token: ', error)
-            ])
+            .catch(error => {
+                console.error('Failed to get user token: ', error)
+            })
         }
 
         function verifyToken(token) {
@@ -345,7 +346,7 @@ header("Allow: GET, POST, OPTIONS, PUT, DELETE");
         function logout() {
             // remove token from global variable and vscode global state
             USERTOKEN = null
-            communicateVSCodeByWebview('setUserToken', { userToken: 'none'})
+            communicateVSCodeByWebview('setUserToken', { userToken: ''})
             .then(result => {
                 if (result.ok) {
                     console.log('User token has been removed from vscode global state')