Fix inverted logic

src/pretix/control/templates/pretixcontrol/order/refund_process.html

@@ -25,7 +25,7 @@
                 <strong>{{ pending }}</strong>. The order total is <strong>{{ total }}</strong>.
             {% endblocktrans %}
         </p>
-        {% if order.status != "c" and order.positions.count > 0 %}
+        {% if order.status == "c" or order.positions.count == 0 %}
             <p>
                 {% blocktrans trimmed %}
                     Since the order is already canceled, this will not affect its state.