internal/glfw: Bug fix: Crash after disconnecting a gamepad on Windows (Wine)

internal/glfw/glfw_windows.go

@@ -338,6 +338,12 @@ func CreateWindow(width, height int, title string, monitor *Monitor, share *Wind
 func (j Joystick) GetGUID() string {
 	ptr := glfwDLL.call("glfwGetJoystickGUID", uintptr(j))
 	panicError()
+
+	// ptr can be nil after disconnecting the joystick.
+	if ptr == 0 {
+		return ""
+	}
+
 	var backed [256]byte
 	as := backed[:0]
 	for i := int32(0); ; i++ {
@@ -355,6 +361,12 @@ func (j Joystick) GetGUID() string {
 func (j Joystick) GetName() string {
 	ptr := glfwDLL.call("glfwGetJoystickName", uintptr(j))
 	panicError()
+
+	// ptr can be nil after disconnecting the joystick.
+	if ptr == 0 {
+		return ""
+	}
+
 	var backed [256]byte
 	as := backed[:0]
 	for i := int32(0); ; i++ {
@@ -373,6 +385,12 @@ func (j Joystick) GetAxes() []float32 {
 	var l int32
 	ptr := glfwDLL.call("glfwGetJoystickAxes", uintptr(j), uintptr(unsafe.Pointer(&l)))
 	panicError()
+
+	// ptr can be nil after disconnecting the joystick.
+	if ptr == 0 {
+		return nil
+	}
+
 	as := make([]float32, l)
 	for i := int32(0); i < l; i++ {
 		as[i] = *(*float32)(unsafe.Pointer(ptr))
@@ -385,6 +403,12 @@ func (j Joystick) GetButtons() []byte {
 	var l int32
 	ptr := glfwDLL.call("glfwGetJoystickButtons", uintptr(j), uintptr(unsafe.Pointer(&l)))
 	panicError()
+
+	// ptr can be nil after disconnecting the joystick.
+	if ptr == 0 {
+		return nil
+	}
+
 	bs := make([]byte, l)
 	for i := int32(0); i < l; i++ {
 		bs[i] = *(*byte)(unsafe.Pointer(ptr))
@@ -397,6 +421,12 @@ func (j Joystick) GetHats() []JoystickHatState {
 	var l int32
 	ptr := glfwDLL.call("glfwGetJoystickHats", uintptr(j), uintptr(unsafe.Pointer(&l)))
 	panicError()
+
+	// ptr can be nil after disconnecting the joystick.
+	if ptr == 0 {
+		return nil
+	}
+
 	hats := make([]JoystickHatState, l)
 	for i := int32(0); i < l; i++ {
 		hats[i] = *(*JoystickHatState)(unsafe.Pointer(ptr))