use new error formatting

src/main.rs

@@ -58,7 +58,7 @@ fn parse_or_error(game_data: String, label: &str) -> Result<Game, ()> {
         Ok(main.unwrap())
     } else {
         error_popup(&format!(
-            "Couldn't parse {} game data: {:?}",
+            "Couldn't parse {} game data.\n\n{}",
             label,
             main.unwrap_err()));
         Err(())
@@ -101,7 +101,7 @@ fn build_ui(application: &gtk::Application) {
         if main.is_ok() && additional.is_ok() {
             let mut main = main.unwrap();
             let additional = additional.unwrap();
-            main.merge(additional);
+            main.merge(&additional);
 
             buffer_output.set_text(&main.to_string());
         }