Fix property reply errors being coerced to 0

During a refactor this changed from a boolean to an option, guess I
missed this.

CHANGELOG.md

@@ -29,10 +29,12 @@ Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### Fixed
 
-- Fixed the drag-and-drop implementation now sending an `XdndStatus` message on
+- Fixed the drag-and-drop implementation not sending an `XdndStatus` message on
   the very first tick. This fixes drag-and-drop from _Samplab_ which has a
   broken drag-and-drop implementation and only starts the operation after the
   left mouse button has already been released.
+- Fixed the drag-and-drop implementation not properly handling errors caused by
+  the pointer being grabbed. This would only happen with _Samplab_.
 
 ### Packaging notes
 

src/wine-host/xdnd-proxy.cpp

@@ -609,7 +609,7 @@ std::optional<uint8_t> WineXdndProxy::is_xdnd_aware(
         xcb_get_property_reply(x11_connection.get(), property_cookie, &error));
     if (error) {
         free(error);
-        return false;
+        return std::nullopt;
     }
 
     // Since the spec dates from 2002, we won't even bother checking the