From d1ddca6718dabf4fa7e54b83b88b8944154740bd Mon Sep 17 00:00:00 2001
From: Elizabeth Esswein <elizabeth.esswein@gmail.com>
Date: Fri, 12 Jul 2024 16:27:35 -0400
Subject: [PATCH] handle certain out of order states in spec migration

---
 SpiffWorkflow/bpmn/util/diff.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/SpiffWorkflow/bpmn/util/diff.py b/SpiffWorkflow/bpmn/util/diff.py
index 9d28d49d..01220be0 100644
--- a/SpiffWorkflow/bpmn/util/diff.py
+++ b/SpiffWorkflow/bpmn/util/diff.py
@@ -218,4 +218,7 @@ def migrate_workflow(diff, workflow, spec, reset_mask=None):
 
     default_mask = TaskState.READY|TaskState.WAITING
     for task in list(workflow.get_tasks(state=reset_mask or default_mask, skip_subprocesses=True)):
-        task.reset_branch(None)
+        # In some cases, completed tasks with ready or waiting children could get removed
+        # (for example, in cycle timer).  If a task has already been removed from the tree, ignore it.
+        if task.id in workflow.tasks:
+            task.reset_branch(None)