chore(code.angular): correctly remove old zip files from snapshot

Previously, the event would be triggered on the deletion of the previous zip files,
which would delete the current zip file as well

Closes #16168

scripts/code.angularjs.org-firebase/functions/index.js

@@ -175,31 +175,33 @@ function deleteOldSnapshotZip(event) {
   const bucketId = object.bucket;
   const filePath = object.name;
   const contentType = object.contentType;
+  const resourceState = object.resourceState;
 
   const bucket = gcs.bucket(bucketId);
 
-  if (event.eventType === 'providers/cloud.storage/eventTypes/object.change' &&
-      contentType === 'application/zip' &&
-      filePath.startsWith('snapshot/')
+  if (contentType !== 'application/zip' ||
+      !filePath.startsWith('snapshot/') ||
+      resourceState === 'not_exists' // Deletion event
     ) {
-
-    bucket.getFiles({
-      prefix: 'snapshot/',
-      delimiter: '/',
-      autoPaginate: false
-    }).then(function(data) {
-      const files = data[0];
-
-      const oldZipFiles = files.filter(file => {
-        return file.metadata.name !== filePath && file.metadata.contentType === 'application/zip';
-      });
-
-      oldZipFiles.forEach(function(file) {
-        file.delete();
-      });
-
-    });
+    return;
   }
+
+  bucket.getFiles({
+    prefix: 'snapshot/',
+    delimiter: '/',
+    autoPaginate: false
+  }).then(function(data) {
+    const files = data[0];
+
+    const oldZipFiles = files.filter(file => {
+      return file.metadata.name !== filePath && file.metadata.contentType === 'application/zip';
+    });
+
+    oldZipFiles.forEach(function(file) {
+      file.delete();
+    });
+
+  });
 }
 
 exports.sendStoredFile = functions.https.onRequest(sendStoredFile);