Remove owned String from CustomError.

This is a 15% performance improvement.

src/error/error.rs

@@ -6,8 +6,6 @@ pub(crate) type Res<T, U> = IResult<T, U, CustomError>;
 
 #[derive(Debug)]
 pub enum CustomError {
-    #[allow(dead_code)]
-    Text(String),
     Static(&'static str),
     IO(std::io::Error),
     Parser(ErrorKind),
@@ -35,9 +33,3 @@ impl From<&'static str> for CustomError {
         CustomError::Static(value)
     }
 }
-
-impl From<String> for CustomError {
-    fn from(value: String) -> Self {
-        CustomError::Text(value)
-    }
-}