feat: parse error

src/error.rs

@@ -4,6 +4,8 @@ pub type Result<T> = core::result::Result<T, Error>;
 
 #[derive(Error, Debug)]
 pub enum Error {
+    #[error("error occurred during parse stage: {0}")]
+    ParseError(String),
     #[error("error occurred during downgrade stage: {0}")]
     DowngradeError(String),
     #[error("error occurred during evaluation stage: {0}")]