fix: 状態遷移関数で定義されていない状態を受理状態に設定できる問題を修正

src/bin.rs

@@ -123,6 +123,7 @@ fn main() -> Result<()> {
 
         if args.is_step_by_step {
             while {
+                term.clear_line()?;
                 print!("Press Enter to continue...");
                 stdout().flush()?;
                 let key = term.read_key()?;
@@ -193,7 +194,27 @@ fn turing_machine_from_config(config: &Config, tape: String) -> Result<TuringMac
     let initial_state = states.get(&config.initial_state.as_str()).unwrap();
     let accept_states = (&config.accept_states)
         .into_iter()
-        .map(|name| states.get(name.as_str()).unwrap().clone())
+        .map(|name| states.get(name.as_str()))
+        .collect::<Vec<_>>();
+    if accept_states.iter().any(|s| s.is_none()) {
+        return Err(anyhow!(
+            "Invalid accept state: {}. Accept state must be one of {}.",
+            config
+                .accept_states
+                .iter()
+                .map(|s| format!("\"{}\"", s))
+                .collect::<Vec<String>>()
+                .join(", "),
+            state_names
+                .iter()
+                .map(|s| format!("\"{}\"", s))
+                .collect::<Vec<String>>()
+                .join(", ")
+        ));
+    }
+    let accept_states = accept_states
+        .into_iter()
+        .map(|s| s.unwrap().clone())
         .collect::<Vec<_>>();
 
     let mut alphabet = config