Introduce MaybeError type

src/data_provider/history.rs

@@ -2,7 +2,7 @@ use crate::core::srs::WordOpenMode;
 use crate::data::Id;
 use crate::data::entities::HistoryItem;
 use crate::fs::*;
-use crate::notification::NotificationData;
+use crate::notification::{MaybeError, NotificationData};
 use crate::notification::NotificationData::PermissionDenied;
 use chrono::DateTime;
 use std::fs::{File, OpenOptions};
@@ -20,7 +20,7 @@ pub fn get_history_of_set(id: Id) -> Result<Vec<HistoryItem>, NotificationData>
     Ok(parse_history_items(lines))
 }
 
-fn append_lines_if_exists(path: PathBuf, lines: &mut Vec<String>) -> Result<(), NotificationData> {
+fn append_lines_if_exists(path: PathBuf, lines: &mut Vec<String>) -> MaybeError {
     if path.exists() {
         let reader = BufReader::new(File::open(path).map_err(|_| PermissionDenied)?);
         reader
@@ -63,7 +63,7 @@ fn parse_history_items(strings: Vec<String>) -> Vec<HistoryItem> {
     items
 }
 
-pub fn push_note(set_id: Id, item: HistoryItem) -> Result<(), NotificationData> {
+pub fn push_note(set_id: Id, item: HistoryItem) -> MaybeError {
     let app_dir = history_dir()?;
     let path = app_dir.clone().join(format!("set_{}_history.csv", set_id));