migrate to v4

scripts/build_one_click_apps.js

@@ -114,9 +114,19 @@ function convertV2toV4(v2String) {
 
 
 function buildDist() {
-    return fs.readdir(pathOfSourceDirectoryApps)
+    return Promise.resolve()
+        .then(function () {
+            if (!fs.existsSync(pathOfSourceDirectoryApps)) {
+                return [];
+            }
+            return fs.readdir(pathOfSourceDirectoryApps);
+        })
         .then(function (appsFileNames) { // [ app1.json app2.json .... ]
 
+            if (appsFileNames.length === 0) {
+                return;
+            }
+
             appsFileNames.forEach(appFileName => {
                 const pathOfAppFileInSource = path.join(pathOfSourceDirectoryApps, appFileName);
 
@@ -143,8 +153,6 @@ function buildDist() {
             fs.outputJsonSync(path.join(pathOfDistV2, 'list'), v3List); // TODO delete oneClickApps: 
             fs.outputJsonSync(path.join(pathOfDistV3, 'list'), v3List);
             fs.outputJsonSync(path.join(pathOfDistV4, 'list'), v3List);
-        })
-        .then(function () {
             return fs.copySync(path.join(pathOfPublic, 'CNAME'), path.join(pathOfDist, 'CNAME'));
         });
 }