ProcessEngineException: Cannot find serializer

Hello,
I’m trying simple script task where i used java script to execute and get some result.When i started the process its executing fine till my custom task and its getting following error at script task:

org.camunda.bpm.engine.ProcessEngineException: Cannot find serializer for value ‘Untyped value ‘[object global]’, isTransient = false’.

Here is my bpmn file:

javascriptBpmn.bpmn (4.8 KB)

Can anyone please help me to sort out this problem