Error by updating a Planner task with label when SharePoint item is modified

[WilcovanEe]

I have a flow to update a planner task when a SharePoint item is modified. The flow gives an error when I want to add a label based on a variable.

First I make the variable (FinalAssignedTo) based on the AssignedTo, then I make the outcome for the label based on the expressoin  "if(contains(variables('FinalAssignedTo'), 'name@domain.com'), 'true', 'false')"

Then I update the Planner task with the outcome from the label.

I get the following error message: "An open type property has an invalid type."

I have the same situation in a flow "New SharePoint item -> Make Planner task". In this flow it is working correct.

Can someone help me to solve this issue?