Introduce MaybeError type

src/pages/import.rs

@@ -4,7 +4,7 @@ use crate::pages::import::ImportMessage::*;
 use crate::data::entities::{WordData, WordGroup};
 use crate::navigation::{NavigatedPage, Page, RootMessage};
 use crate::notification::NotificationData::OpenFileError;
-use crate::notification::NotificationData;
+use crate::notification::{MaybeError, NotificationData};
 use crate::styling::*;
 use iced::widget::button::danger;
 use iced::widget::container::success;
@@ -373,7 +373,7 @@ impl ImportState {
         )
     }
 
-    fn extract_import_file(path: PathBuf) -> Result<(), NotificationData> {
+    fn extract_import_file(path: PathBuf) -> MaybeError {
         let file = File::open(path).map_err(|_| OpenFileError)?;
         let reader = BufReader::new(file);
         let mut archive = ZipArchive::new(reader).map_err(|_| OpenFileError)?;