flow designer - getting task info from previous task in flow, and using it in approval action

[cameron8]

I've got a scenario where i'm generating a catalog task in a flow. I need to take whomever is the assigned to or user that closes the task, and make them the approver on a subsequent approval action. its giving me the following error: 

class com.snc.process_flow.engine.serialization.GRProxy$1 cannot be cast to class java.lang.String (com.snc.process_flow.engine.serialization.GRProxy$1 is in unnamed module of loader com.snc.orbit.container.tomcat8.Tomcat8$OrbitTomcat8ClassLoader @12798a4b; java.lang.String is in module java.base of loader 'bootstrap')

catalog task creation:

looking up data from cat task 

then trying to pull the closed by OR assigned to from the previous task in step/action 3, and using it in the approval:

[J Siva]

Hi @cameron8 

Please verify the step "Lookup Catalog task" (step 4).

Actually it doesn't have valid condition.

The Lookup condition should be something like "sys_id is <fetch sys_id from the previous step>"

Regards,

Siva