chore: introduce AppEventSender to help fix clippy warnings and update to Rust 1.87 (#948)

Moving to Rust 1.87 introduced a clippy warning that
`SendError<AppEvent>` was too large.

In practice, the only thing we ever did when we got this error was log
it (if the mspc channel is closed, then the app is likely shutting down
or something, so there's not much to do...), so this finally motivated
me to introduce `AppEventSender`, which wraps
`std::sync::mpsc::Sender<AppEvent>` with a `send()` method that invokes
`send()` on the underlying `Sender` and logs an `Err` if it gets one.

This greatly simplifies the code, as many functions that previously
returned `Result<(), SendError<AppEvent>>` now return `()`, so we don't
have to propagate an `Err` all over the place that we don't really
handle, anyway.

This also makes it so we can upgrade to Rust 1.87 in CI.

codex-rs/tui/src/bottom_pane/mod.rs

@@ -6,10 +6,9 @@ use crossterm::event::KeyEvent;
 use ratatui::buffer::Buffer;
 use ratatui::layout::Rect;
 use ratatui::widgets::WidgetRef;
-use std::sync::mpsc::SendError;
-use std::sync::mpsc::Sender;
 
 use crate::app_event::AppEvent;
+use crate::app_event_sender::AppEventSender;
 use crate::user_approval_widget::ApprovalRequest;
 
 mod approval_modal_view;
@@ -33,13 +32,13 @@ pub(crate) struct BottomPane<'a> {
     /// If present, this is displayed instead of the `composer`.
     active_view: Option<Box<dyn BottomPaneView<'a> + 'a>>,
 
-    app_event_tx: Sender<AppEvent>,
+    app_event_tx: AppEventSender,
     has_input_focus: bool,
     is_task_running: bool,
 }
 
 pub(crate) struct BottomPaneParams {
-    pub(crate) app_event_tx: Sender<AppEvent>,
+    pub(crate) app_event_tx: AppEventSender,
     pub(crate) has_input_focus: bool,
 }
 
@@ -55,12 +54,9 @@ impl BottomPane<'_> {
     }
 
     /// Forward a key event to the active view or the composer.
-    pub fn handle_key_event(
-        &mut self,
-        key_event: KeyEvent,
-    ) -> Result<InputResult, SendError<AppEvent>> {
+    pub fn handle_key_event(&mut self, key_event: KeyEvent) -> InputResult {
         if let Some(mut view) = self.active_view.take() {
-            view.handle_key_event(self, key_event)?;
+            view.handle_key_event(self, key_event);
             if !view.is_complete() {
                 self.active_view = Some(view);
             } else if self.is_task_running {
@@ -70,31 +66,30 @@ impl BottomPane<'_> {
                     height,
                 )));
             }
-            self.request_redraw()?;
-            Ok(InputResult::None)
+            self.request_redraw();
+            InputResult::None
         } else {
             let (input_result, needs_redraw) = self.composer.handle_key_event(key_event);
             if needs_redraw {
-                self.request_redraw()?;
+                self.request_redraw();
             }
-            Ok(input_result)
+            input_result
         }
     }
 
     /// Update the status indicator text (only when the `StatusIndicatorView` is
     /// active).
-    pub(crate) fn update_status_text(&mut self, text: String) -> Result<(), SendError<AppEvent>> {
+    pub(crate) fn update_status_text(&mut self, text: String) {
         if let Some(view) = &mut self.active_view {
             match view.update_status_text(text) {
                 ConditionalUpdate::NeedsRedraw => {
-                    self.request_redraw()?;
+                    self.request_redraw();
                 }
                 ConditionalUpdate::NoRedraw => {
                     // No redraw needed.
                 }
             }
         }
-        Ok(())
     }
 
     /// Update the UI to reflect whether this `BottomPane` has input focus.
@@ -103,7 +98,7 @@ impl BottomPane<'_> {
         self.composer.set_input_focus(has_focus);
     }
 
-    pub fn set_task_running(&mut self, running: bool) -> Result<(), SendError<AppEvent>> {
+    pub fn set_task_running(&mut self, running: bool) {
         self.is_task_running = running;
 
         match (running, self.active_view.is_some()) {
@@ -114,13 +109,13 @@ impl BottomPane<'_> {
                     self.app_event_tx.clone(),
                     height,
                 )));
-                self.request_redraw()?;
+                self.request_redraw();
             }
             (false, true) => {
                 if let Some(mut view) = self.active_view.take() {
                     if view.should_hide_when_task_is_done() {
                         // Leave self.active_view as None.
-                        self.request_redraw()?;
+                        self.request_redraw();
                     } else {
                         // Preserve the view.
                         self.active_view = Some(view);
@@ -131,20 +126,16 @@ impl BottomPane<'_> {
                 // No change.
             }
         }
-        Ok(())
     }
 
     /// Called when the agent requests user approval.
-    pub fn push_approval_request(
-        &mut self,
-        request: ApprovalRequest,
-    ) -> Result<(), SendError<AppEvent>> {
+    pub fn push_approval_request(&mut self, request: ApprovalRequest) {
         let request = if let Some(view) = self.active_view.as_mut() {
             match view.try_consume_approval_request(request) {
                 Some(request) => request,
                 None => {
-                    self.request_redraw()?;
-                    return Ok(());
+                    self.request_redraw();
+                    return;
                 }
             }
         } else {
@@ -166,7 +157,7 @@ impl BottomPane<'_> {
         }
     }
 
-    pub(crate) fn request_redraw(&self) -> Result<(), SendError<AppEvent>> {
+    pub(crate) fn request_redraw(&self) {
         self.app_event_tx.send(AppEvent::Redraw)
     }