added invalid_handle err

protocols/hyprland-toplevel-export-v1.xml

@@ -142,6 +142,8 @@
         summary="the object has already been used to copy a wl_buffer"/>
       <entry name="invalid_buffer" value="1"
         summary="buffer attributes are invalid"/>
+      <entry name="invalid_handle" value="2"
+        summary="the handle is invalid. The window may not exist or be unshareable (e.g. unmapped)"/>
     </enum>
 
     <enum name="flags" bitfield="true">