fix: properly handle removing the last split dns record

Previously it would set the value to an empty array, breaking DNS resolution for that split completely.
The correct behavior was to remove the key altogether! This fixes #231

app/routes/dns/dns-actions.ts

@@ -104,7 +104,7 @@ async function removeNs(formData: FormData, context: LoadContext) {
 		await context.hs.patch([
 			{
 				path: `dns.nameservers.split."${splitName}"`,
-				value: servers,
+				value: servers.length > 0 ? servers : null,
 			},
 		]);
 	}