GraphQL Abstract type Node must resolve to an Object type at runtime for field RootQueryType.node with value "[object Object]", received "null

I am trying to set up signIn functionality using Relay-GraphQL and I am facing this error when I am setting the RelayVariables.

Abstract type Node must resolve to an Object type at runtime for field RootQueryType.node with value "[object Object]", received "null"

The workflow is like, when user clicks signIn button then signIn component is displayed with initialvaribales of username and password as empty strings. After inserting the values, on click of signIn button I am setting the RelayVariables. I am unable to understand the source of error.

If I am making a request from GraphQL it is running well.

Thank you.

via Rahul