Is it possible to suppress error message "Uncaught (In promise) error: the scenario is currently locked and cannot be updated" popping out at the bottom of the screen?

That is because the VDL Action <vdl-action-update-entity> only sends the update to the model and then returns straight away. The next Action is triggered but the update to the model may not have resulted in an update on the view.

In this case, if you don't need to persist the value in the model, could you use a Vdl Var instead? https://www.fico.com/fico-xpress-optimization/docs/latest/insight5/vdl_reference/vdl-var.html

And substitute <vdl-action-set-var> https://www.fico.com/fico-xpress-optimization/docs/latest/insight5/vdl_reference/vdl-action-set-var.html