Fix some clippy warnings

src/cli/error.rs

@@ -1,6 +1,5 @@
 use std::result;
 
-use crate::files::Source;
 use crate::{eval, files};
 
 #[derive(Debug, thiserror::Error)]

src/cli/layout/line.rs

@@ -101,14 +101,6 @@ impl LineLayout {
         &self.lines
     }
 
-    /// Return a map from entry indices to their corresponding display numbers.
-    ///
-    /// If you need to resolve a display number into an entry index, use
-    /// [`Self::look_up_number`] instead.
-    pub fn numbers(&self) -> &HashMap<usize, usize> {
-        &self.numbers
-    }
-
     pub fn look_up_number(&self, number: usize) -> Result<usize> {
         self.numbers
             .iter()