Handle failure when enabling bracketed paste (helix-editor#9353)

* match instead of crash

* pulling bracketedpaste out, refactor, tracking for bracketed paste

* sending disable bracketed paste only when supports true

* move disable bracketed paste to throwaway

helix-tui/src/backend/crossterm.rs

@@ -79,6 +79,7 @@ pub struct CrosstermBackend<W: Write> {
     capabilities: Capabilities,
     supports_keyboard_enhancement_protocol: OnceCell<bool>,
     mouse_capture_enabled: bool,
+    supports_bracketed_paste: bool,
 }
 
 impl<W> CrosstermBackend<W>
@@ -91,6 +92,7 @@ where
             capabilities: Capabilities::from_env_or_default(config),
             supports_keyboard_enhancement_protocol: OnceCell::new(),
             mouse_capture_enabled: false,
+            supports_bracketed_paste: true,
         }
     }
 
@@ -134,9 +136,16 @@ where
         execute!(
             self.buffer,
             terminal::EnterAlternateScreen,
-            EnableBracketedPaste,
             EnableFocusChange
         )?;
+        match execute!(self.buffer, EnableBracketedPaste,) {
+            Err(err) if err.kind() == io::ErrorKind::Unsupported => {
+                log::warn!("Bracketed paste is not supported on this terminal.");
+                self.supports_bracketed_paste = false;
+            }
+            Err(err) => return Err(err),
+            Ok(_) => (),
+        };
         execute!(self.buffer, terminal::Clear(terminal::ClearType::All))?;
         if config.enable_mouse_capture {
             execute!(self.buffer, EnableMouseCapture)?;
@@ -177,9 +186,11 @@ where
         if self.supports_keyboard_enhancement_protocol() {
             execute!(self.buffer, PopKeyboardEnhancementFlags)?;
         }
+        if self.supports_bracketed_paste {
+            execute!(self.buffer, DisableBracketedPaste,)?;
+        }
         execute!(
             self.buffer,
-            DisableBracketedPaste,
             DisableFocusChange,
             terminal::LeaveAlternateScreen
         )?;
@@ -195,12 +206,8 @@ where
         // disable without calling enable previously
         let _ = execute!(stdout, DisableMouseCapture);
         let _ = execute!(stdout, PopKeyboardEnhancementFlags);
-        execute!(
-            stdout,
-            DisableBracketedPaste,
-            DisableFocusChange,
-            terminal::LeaveAlternateScreen
-        )?;
+        let _ = execute!(stdout, DisableBracketedPaste);
+        execute!(stdout, DisableFocusChange, terminal::LeaveAlternateScreen)?;
         terminal::disable_raw_mode()
     }