Don't panic if we get an unexpected key code

It seems like we get media play/pause/mute/etc keys despite not
emitting DISAMBIGUATE_ESCAPE_CODES(#4125).

Make crossterm::event::KeyCode a TryInto for KeyCode instead of Into to
let us ignore keys we don't care about.

helix-term/src/application.rs

@@ -538,14 +538,22 @@ impl Application {
             jobs: &mut self.jobs,
             scroll: None,
         };
-        // Handle key events
         let should_redraw = match event.unwrap() {
             CrosstermEvent::Resize(width, height) => {
                 self.compositor.resize(width, height);
                 self.compositor
                     .handle_event(&Event::Resize(width, height), &mut cx)
             }
-            event => self.compositor.handle_event(&event.into(), &mut cx),
+            event => match &event.try_into() {
+                Ok(event) => self.compositor.handle_event(&event, &mut cx),
+                Err(err) => {
+                    log::warn!(
+                        "Unable to convert crossterm event to helix event. Ignoring. Cause: {}",
+                        err
+                    );
+                    false
+                }
+            },
         };
 
         if should_redraw && !self.editor.should_close() {

helix-view/src/input.rs

@@ -276,16 +276,17 @@ impl<'de> Deserialize<'de> for KeyEvent {
 }
 
 #[cfg(feature = "term")]
-impl From<crossterm::event::Event> for Event {
-    fn from(event: crossterm::event::Event) -> Self {
-        match event {
-            crossterm::event::Event::Key(key) => Self::Key(key.into()),
+impl TryFrom<crossterm::event::Event> for Event {
+    type Error = anyhow::Error;
+    fn try_from(event: crossterm::event::Event) -> Result<Self, Error> {
+        Ok(match event {
+            crossterm::event::Event::Key(key) => Self::Key(key.try_into()?),
             crossterm::event::Event::Mouse(mouse) => Self::Mouse(mouse.into()),
             crossterm::event::Event::Resize(w, h) => Self::Resize(w, h),
             crossterm::event::Event::FocusGained => Self::FocusGained,
             crossterm::event::Event::FocusLost => Self::FocusLost,
             crossterm::event::Event::Paste(s) => Self::Paste(s),
-        }
+        })
     }
 }
 
@@ -334,25 +335,26 @@ impl From<crossterm::event::MouseButton> for MouseButton {
 }
 
 #[cfg(feature = "term")]
-impl From<crossterm::event::KeyEvent> for KeyEvent {
-    fn from(
+impl TryFrom<crossterm::event::KeyEvent> for KeyEvent {
+    type Error = anyhow::Error;
+    fn try_from(
         crossterm::event::KeyEvent {
             code, modifiers, ..
         }: crossterm::event::KeyEvent,
-    ) -> Self {
+    ) -> Result<Self, Error> {
         if code == crossterm::event::KeyCode::BackTab {
             // special case for BackTab -> Shift-Tab
             let mut modifiers: KeyModifiers = modifiers.into();
             modifiers.insert(KeyModifiers::SHIFT);
-            Self {
+            Ok(Self {
                 code: KeyCode::Tab,
                 modifiers,
-            }
+            })
         } else {
-            Self {
-                code: code.into(),
+            Ok(Self {
+                code: code.try_into()?,
                 modifiers: modifiers.into(),
-            }
+            })
         }
     }
 }

helix-view/src/keyboard.rs

@@ -1,3 +1,4 @@
+use anyhow::{bail, Error};
 use bitflags::bitflags;
 
 bitflags! {
@@ -124,11 +125,12 @@ impl From<KeyCode> for crossterm::event::KeyCode {
 }
 
 #[cfg(feature = "term")]
-impl From<crossterm::event::KeyCode> for KeyCode {
-    fn from(val: crossterm::event::KeyCode) -> Self {
+impl TryFrom<crossterm::event::KeyCode> for KeyCode {
+    type Error = Error;
+    fn try_from(val: crossterm::event::KeyCode) -> Result<Self, Error> {
         use crossterm::event::KeyCode as CKeyCode;
 
-        match val {
+        Ok(match val {
             CKeyCode::Backspace => KeyCode::Backspace,
             CKeyCode::Enter => KeyCode::Enter,
             CKeyCode::Left => KeyCode::Left,
@@ -155,9 +157,9 @@ impl From<crossterm::event::KeyCode> for KeyCode {
             | CKeyCode::Menu
             | CKeyCode::KeypadBegin
             | CKeyCode::Media(_)
-            | CKeyCode::Modifier(_) => unreachable!(
+            | CKeyCode::Modifier(_) => bail!(
                 "Shouldn't get this key without enabling DISAMBIGUATE_ESCAPE_CODES in crossterm"
             ),
-        }
+        })
     }
 }