Add an owned string entry for CustomError.

src/parser/org_source.rs

@@ -402,6 +402,7 @@ impl<'s> From<CustomError<OrgSource<'s>>> for CustomError<&'s str> {
             CustomError::Nom(input, error_kind) => CustomError::Nom(input.into(), error_kind),
             CustomError::IO(err) => CustomError::IO(err),
             CustomError::BoxedError(err) => CustomError::BoxedError(err),
+            CustomError::Text(err) => CustomError::Text(err),
         }
     }
 }