ensure fallback certificates of all domains

https://forum.cloudron.io/topic/5683/data-argument-must-be-of-type-received-null-error-during-restore-process

src/domains.js

@@ -142,7 +142,6 @@ async function add(domain, data, auditSource) {
         if (error) throw error;
     } else {
         fallbackCertificate = await reverseProxy.generateFallbackCertificate(domain);
-        if (fallbackCertificate.error) throw fallbackCertificate.error;
     }
 
     let error = validateTlsConfig(tlsConfig, provider);