[processing] fix python error with OSM vector layers

Author: nirvn

python/plugins/processing/gui/wrappers.py

@@ -1027,7 +1027,7 @@ def createWidget(self):
             return widget
 
     def layerChanged(self, layer):
-        if not layer or layer.type() != QgsMapLayer.VectorLayer or layer.selectedFeatureCount() == 0:
+        if layer is not None or layer.type() != QgsMapLayer.VectorLayer or layer.selectedFeatureCount() == 0:
             self.use_selection_checkbox.setChecked(False)
             self.use_selection_checkbox.setEnabled(False)
         else: