Fix a crash when dismissing the tip of the day with the keyboard (esc)

sources/iTermCarbonHotKeyController.m

@@ -273,9 +273,14 @@ static OSStatus EventHandler(EventHandlerCallRef inHandler,
             continue;
         }
         // The target returns an array of siblings that were handled at the same time.
-        [handled addObjectsFromArray:[hotkey.target performSelector:hotkey.selector
-                                                         withObject:hotkey.userData
-                                                         withObject:[hotkeys arrayByRemovingObject:hotkey]]];
+        NSArray *handledSiblings = [hotkey.target performSelector:hotkey.selector
+                                                       withObject:hotkey.userData
+                                                       withObject:[hotkeys arrayByRemovingObject:hotkey]];
+        if (handledSiblings) {
+            [handled addObjectsFromArray:handledSiblings];
+        } else {
+            [handled addObject:hotkey];
+        }
     }
     return hotkeys.count > 0;

sources/iTermTipWindowController.m

@@ -278,8 +278,9 @@ static const CGFloat kWindowWidth = 400;
     return nil;
 }
-- (void)dismissByKeyboard:(id)sender {
+- (NSArray *)dismissByKeyboard:(id)sender {
     [self dismiss];
+    return nil;
 }
 // Update the card's size.