project: Use checked_sub for next/previous in search history (#34408)

Use `checked_sub` instead of checking for bounds manually. Also greatly
simplifies the logic for `next` and `previous`. Removing other manual
bounds checks as well

Release Notes:

- N/A

crates/project/src/search_history.rs

@@ -72,18 +72,12 @@ impl SearchHistory {
     }
 
     pub fn next(&mut self, cursor: &mut SearchHistoryCursor) -> Option<&str> {
-        let history_size = self.history.len();
-        if history_size == 0 {
-            return None;
-        }
-
         let selected = cursor.selection?;
-        if selected == history_size - 1 {
-            return None;
-        }
         let next_index = selected + 1;
+
+        let next = self.history.get(next_index)?;
         cursor.selection = Some(next_index);
-        Some(&self.history[next_index])
+        Some(next)
     }
 
     pub fn current(&self, cursor: &SearchHistoryCursor) -> Option<&str> {
@@ -92,25 +86,17 @@ impl SearchHistory {
             .and_then(|selected_ix| self.history.get(selected_ix).map(|s| s.as_str()))
     }
 
+    /// Get the previous history entry using the given `SearchHistoryCursor`.
+    /// Uses the last element in the history when there is no cursor.
     pub fn previous(&mut self, cursor: &mut SearchHistoryCursor) -> Option<&str> {
-        let history_size = self.history.len();
-        if history_size == 0 {
-            return None;
-        }
-
         let prev_index = match cursor.selection {
-            Some(selected_index) => {
-                if selected_index == 0 {
-                    return None;
-                } else {
-                    selected_index - 1
-                }
-            }
-            None => history_size - 1,
+            Some(index) => index.checked_sub(1)?,
+            None => self.history.len().checked_sub(1)?,
         };
 
+        let previous = self.history.get(prev_index)?;
         cursor.selection = Some(prev_index);
-        Some(&self.history[prev_index])
+        Some(previous)
     }
 }
 

crates/project/src/terminals.rs

@@ -169,7 +169,7 @@ impl Project {
             .read(cx)
             .get_cli_environment()
             .unwrap_or_default();
-        env.extend(settings.env.clone());
+        env.extend(settings.env);
 
         match self.ssh_details(cx) {
             Some(SshDetails {
@@ -247,7 +247,7 @@ impl Project {
             .unwrap_or_default();
         // Then extend it with the explicit env variables from the settings, so they take
         // precedence.
-        env.extend(settings.env.clone());
+        env.extend(settings.env);
 
         let local_path = if is_ssh_terminal { None } else { path.clone() };