Error when trying to set n-window

[ColemanTom]

I don't have much detail. I just noticed a workflow was shutdown I didn't think should be. Looked in the scheduler log and saw this error.

2025-06-12T07:14:13Z INFO - Command "set_graph_window_extent" received.
    set_graph_window_extent(n_edge_distance=0)
2025-06-12T07:14:14Z CRITICAL - An uncaught error caused Cylc to shut down.
    If you think this was an issue in Cylc, please report the following traceback to the developers.
    https://github.com/cylc/cylc-flow/issues/new?assignees=&labels=bug&template=bug.md&title=;
2025-06-12T07:14:14Z ERROR - 'bool' object has no attribute 'flow_nums'
    Traceback (most recent call last):
      File "/home/miniconda3/envs/cylc-8.3.6/lib/python3.11/site-packages/cylc/flow/scheduler_cli.py", line 689, in cylc_play
        asyncio.get_running_loop()
    RuntimeError: no running event loop
    During handling of the above exception, another exception occurred:
    Traceback (most recent call last):
      File "/home/miniconda3/envs/cylc-8.3.6/lib/python3.11/site-packages/cylc/flow/scheduler.py", line 652, in run_scheduler
        await self._main_loop()
      File "/home/miniconda3/envs/cylc-8.3.6/lib/python3.11/site-packages/cylc/flow/scheduler.py", line 1557, in _main_loop
        await self.update_data_structure()
      File "/home/miniconda3/envs/cylc-8.3.6/lib/python3.11/site-packages/cylc/flow/scheduler.py", line 1639, in update_data_structure
        self.data_store_mgr.update_data_structure()
      File "/home/miniconda3/envs/cylc-8.3.6/lib/python3.11/site-packages/cylc/flow/data_store_mgr.py", line 1717, in update_data_structure
        self.window_resize_rewalk()
      File "/home/miniconda3/envs/cylc-8.3.6/lib/python3.11/site-packages/cylc/flow/data_store_mgr.py", line 1788, in window_resize_rewalk
        deserialise_set(tproxy.flow_nums)
                        ^^^^^^^^^^^^^^^^
    AttributeError: 'bool' object has no attribute 'flow_nums'
2025-06-12T07:14:14Z CRITICAL - Workflow shutting down - 'bool' object has no attribute 'flow_nums'
2025-06-12T07:14:14Z WARNING - Orphaned tasks:
    * 20250612T0000Z/simpler_egress_gfe_144_gl (submitted)
2025-06-12T07:14:14Z INFO - platform: my_platform- remote tidy (on remote.host)
2025-06-12T07:14:24Z INFO - DONE

It looks like I tried to set the n-window, an error happened, and the workflow shutdown.

NOTE: Cylc UI 2.6.0 in case that matters, and as you can see cylc-flow=8.3.6

[MetRonnie]

This would appear to be caused by a task existing in the task pool but not the data store: https://github.com/cylc/cylc-flow/blob/4db73a2061f93a4b72dafbf85efd38cce8f570e2/cylc/flow/data_store_mgr.py#L1801-L1809

With self.store_node_fetcher(tokens) returning _, False.

This shouldn't be possible, maybe it is fixed in Cylc 8.4 as this rings a bell, but I can't find a matching issue/PR right now

[dwsutherland]

I think the whole data-store window creation (...etc) may have changed since 8.3.6