fix: cover all nilable writer kinds

client.go

@@ -44,7 +44,7 @@ func WithQRWriter(writer io.Writer) Option {
 		if !isNil {
 			value := reflect.ValueOf(writer)
 			switch value.Kind() {
-			case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice:
+			case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice, reflect.UnsafePointer:
 				isNil = value.IsNil()
 			}
 		}