Cancel inline assist editor on blur if it wasn't confirmed (#12684)

Release Notes:

- N/A

crates/assistant/src/inline_assistant.rs

@@ -697,10 +697,18 @@ impl InlineAssistEditor {
         event: &EditorEvent,
         cx: &mut ViewContext<Self>,
     ) {
-        if let EditorEvent::Edited = event {
+        match event {
+            EditorEvent::Edited => {
                 self.pending_prompt = self.prompt_editor.read(cx).text(cx);
                 cx.notify();
             }
+            EditorEvent::Blurred => {
+                if !self.confirmed {
+                    cx.emit(InlineAssistEditorEvent::Canceled);
+                }
+            }
+            _ => {}
+        }
     }
 
     fn handle_codegen_changed(&mut self, _: Model<Codegen>, cx: &mut ViewContext<Self>) {