fix: export error module

Author: liuq19

src/error.rs

@@ -442,7 +442,7 @@ impl ser::Error for Error {
 
 // TODO: remove me in 0.4 version.
 #[cold]
-pub fn make_error(mut msg: String) -> Error {
+pub(crate) fn make_error(mut msg: String) -> Error {
     let (line, column) = parse_line_col(&mut msg).unwrap_or((0, 0));
     Error {
         err: Box::new(ErrorImpl {

src/lib.rs

@@ -3,7 +3,7 @@
 #![doc(test(attr(warn(unused))))]
 
 mod config;
-mod error;
+pub mod error;
 mod index;
 mod input;
 mod parser;