fix: return empty vec

src/certs.rs

@@ -8,6 +8,9 @@ pub async fn read_certs(
     ca: &PublicKey,
     path: impl AsRef<Path>,
 ) -> anyhow::Result<Vec<Certificate>> {
+    if !path.as_ref().exists() {
+        return Ok(Vec::new());
+    }
     read_dir(path.as_ref().join(ca_dir(ca))).await
 }