Update aw-server/src/android/mod.rs

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

Author: 0xbrayo

aw-server/src/android/mod.rs

@@ -257,6 +257,9 @@ pub mod android {
         hostname: JString,
     ) -> jstring {
         let hostname = jstring_to_string(&env, hostname);
+        if hostname.is_empty() {
+            return create_error_object(&env, "hostname must not be empty".to_string());
+        }
         match openDatastore().migrate_hostname(&hostname) {
             Ok(count) => {
                 string_to_jstring(&env, format!("Migrated hostname for {} bucket(s)", count))