Use is_valid for Id

src/repetition.rs

@@ -1,5 +1,6 @@
 use crate::data_provider::voice::get_voice;
-use crate::lang::{DeckData, DeckSettings, CardStatistics, WordData, WordOpenMode};
+use crate::lang::Id;
+use crate::lang::{CardStatistics, DeckData, DeckSettings, WordData, WordOpenMode};
 use crate::navigation::Page::PreviousPage;
 use crate::navigation::{KeyPressedPage, NavigatedPage, Page};
 use crate::styling::*;
@@ -13,7 +14,6 @@ use iced::{Element, Fill, Task, Theme, alignment, keyboard};
 use rodio::MixerDeviceSink;
 use std::collections::HashSet;
 use std::sync::{Arc, Mutex};
-use crate::lang::Id;
 use tokio::task::spawn_blocking;
 
 pub struct RepetitionState {