bug fix

test/dummy/app/controllers/workflows/instances/tokens_controller.rb

@@ -39,7 +39,7 @@ module Workflows
 
     def set_form_model
       @form = @workflow.form
-      overrides = @token.place.output_transition.options.field_overrides.map { |o| {o.name => {accessibility: o.accessibility}} }.reduce(&:merge)
+      overrides = @token.place.output_transition.options.field_overrides.map { |o| {o.name => {accessibility: o.accessibility}} }.reduce(&:merge) || {}
       @virtual_model = @form.to_virtual_model overrides: overrides
     end
 

test/dummy/app/models/workflow.rb

@@ -19,10 +19,11 @@ class Workflow < WorkflowCore::Workflow
     c = Bpmn::DefinitionContainer.parse(bpmn_xml)
     return unless c
 
+    tokens.delete_all
+    instances.delete_all
+
     transitions.destroy_all
     places.destroy_all
-    instances.destroy_all
-    tokens.destroy_all
 
     place = create_start_place! type: "Places::StartPlace"
     node_queue = c.start_event.outgoing_ids