[processing] fix exception raising (fix #11842)

Author: alexbruy

python/plugins/processing/gui/AlgorithmDialog.py

@@ -63,7 +63,7 @@ def setParamValues(self):
                 continue
             if not self.setParamValue(
                     param, self.mainWidget.valueItems[param.name]):
-                raise algHelp.InvalidParameterValue(param,
+                raise AlgorithmDialogBase.InvalidParameterValue(param,
                         self.mainWidget.valueItems[param.name])
 
         for param in params: