Continue removing MyError.

src/parser/headline.rs

@@ -285,9 +285,9 @@ fn priority_cookie(input: OrgSource<'_>) -> Res<OrgSource<'_>, PriorityCookie> {
         tag("]"),
     ))(input)?;
     let cookie = PriorityCookie::try_from(priority_character).map_err(|_| {
-        nom::Err::Error(CustomError::MyError(MyError(
+        nom::Err::Error(CustomError::Static(
             "Failed to cast priority cookie to number.",
-        )))
+        ))
     })?;
     Ok((remaining, cookie))
 }