message: rustfmt + fix error message
diff: @@ -93,7 +93,7 @@ fn extract_private_key(private_key_js: JsValue) -> Result<PrivateKey, JsValue> {
  }
  Err(JsValue::from(
  - "Private key must be encoded as hexstring, base64 or buffer",
  + "Private key must be encoded as base64 string or be a buffer",
  ))
  }
  