icepick: don't open a Keyfork client if not deriving keys

crates/icepick/src/cli/mod.rs

@@ -23,6 +23,9 @@ pub fn derive_keys(
     path_prefix: &DerivationPath,
     accounts: &[DerivationIndex],
 ) -> Vec<Vec<u8>> {
+    if accounts.is_empty() {
+        return vec![];
+    }
     let mut derived_keys = vec![];
     let mut client = keyforkd_client::Client::discover_socket().expect("keyforkd started");
     for account in accounts {