Qt: Fix potential crash if a gamepad causes focus to change

CHANGES

@@ -20,6 +20,7 @@ Bugfixes:
  - Qt: Fix regression where video would not record if the game had already started
  - GBA: Fix rewind boundary conditions
  - GBA: Add initial I/O register settings for background matrix registers
+ - Qt: Fix potential crash if a gamepad causes focus to change
 Misc:
  - Qt: Show multiplayer numbers in window title
 

src/platform/qt/InputController.cpp

@@ -290,6 +290,10 @@ void InputController::testGamepad() {
 		QApplication::sendEvent(QApplication::focusWidget(), event);
 	}
 
+	if (!QApplication::focusWidget()) {
+		return;
+	}
+
 	activeButtons.subtract(oldButtons);
 	oldButtons.subtract(m_activeButtons);