Incorporate feedback

- Empty function removed
- Placeholder and Maxlength restored
- Validation improved
- Typo fixed

backend/migrations/20210423103500_stream_domain.js

@@ -1,4 +1,4 @@
-const migrate_name = 'scream-domain';
+const migrate_name = 'stream_domain';
 const logger       = require('../logger').migrate;
 
 /**