downloader works with each alone and both together

app.js

@@ -174,7 +174,10 @@ function streamFilesToZip(){
 					backendContent = fs.readFileAsync(file.path);
 					backendContent.then(function(data){
 						addBackendToZip(data).then(function(){
-							resolve(finishedArray.push('backend finished'));
+							finishedArray.push('backend finished');
+							if(finishedArray.length === promiseArray.length){
+								resolve(zip);
+							}
 
 						})
 
@@ -193,7 +196,10 @@ function streamFilesToZip(){
 
 					}).on('finish', function(){
 						console.log('zip in frontend:', zip);
-						resolve(finishedArray.push('frontend finished'));
+						finishedArray.push('frontend finished');
+						if(finishedArray.length === promiseArray.length){
+							resolve(zip);
+						}
 						console.log('finishedArray in frontend:', finishedArray);
 
 
@@ -213,24 +219,10 @@ function streamFilesToZip(){
 	})
 }
 
-function collectFilesToZip(finishedArray){
-	console.log('in collectFilesToZip');
-	console.log('finishedArray.length:', finishedArray.length);
-	console.log('promiseArray.length:', promiseArray.length);
-	return new Promise((resolve,reject)=> {
-		if(finishedArray.length === promiseArray.length){
-			console.log('in resolve()');
-			resolve(zip);
-		}
-	})
-}
 
 function finalizeZip(){
-	return streamFilesToZip().then(function(){
-		return collectFilesToZip(finishedArray).then(function(zip){
-
+	return streamFilesToZip().then(function(zip){
 		return createZip(zip)
-		})
 	}).catch(function(error) {let response = 
 		'There was an error during your build. ' +
 		'Please contact "explorviz-developers-request@listserv.dfn.de" ' +