In the last few days, anaconda-webui install tests on aarch64 have failed a few times with the same error, e.g. here:

https://openqa.fedoraproject.org/tests/4036372#step/disk_guided_empty/7

the error is "TypeError: can't access property "initializationMode", $i.find(...) is undefined". From the journal, it seems to happen during storage discovery:

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Dec 02 05:45:54 localhost-live org.fedoraproject.Anaconda.Modules.Storage[3141]: DEBUG:blivet: DeviceTree.get_device_by_device_id returned existing 15 GiB disk vda (13)
Dec 02 05:45:54 localhost-live org.fedoraproject.Anaconda.Modules.Storage[3141]: DEBUG:blivet: DeviceTree.get_device_by_device_id: device_id: vda ; incomplete: True ; hidden: True ;
Dec 02 05:45:54 localhost-live org.fedoraproject.Anaconda.Modules.Storage[3141]: DEBUG:blivet: DeviceTree.get_device_by_device_id returned existing 15 GiB disk vda (13)
Dec 02 05:45:54 localhost-live org.fedoraproject.Anaconda.Modules.Storage[3141]: DEBUG:blivet: DeviceTree.get_device_by_device_id: device_id: vda ; incomplete: True ; hidden: True ;
Dec 02 05:45:54 localhost-live org.fedoraproject.Anaconda.Modules.Storage[3141]: DEBUG:blivet: DeviceTree.get_device_by_device_id returned existing 15 GiB disk vda (13)
Dec 02 05:45:54 localhost-live anaconda-webui[4009]: ErrorBoundary caught an error: TypeError: can't access property "initializationMode", $i.find(...) is undefined
Dec 02 05:45:54 localhost-live org.fedoraproject.Anaconda.Modules.Storage[3141]: DEBUG:blivet: DeviceTree.get_device_by_device_id: device_id: vda ; incomplete: True ; hidden: True ;
Dec 02 05:45:54 localhost-live org.fedoraproject.Anaconda.Modules.Storage[3141]: DEBUG:blivet: DeviceTree.get_device_by_device_id returned existing 15 GiB disk vda (13)
Dec 02 05:45:56 localhost-live org.fedoraproject.Anaconda.Modules.Storage[3141]: DEBUG:blivet: EFIFS.supported: supported: True ;
Dec 02 05:45:56 localhost-live org.fedoraproject.Anaconda.Modules.Storage[3141]: DEBUG:blivet:get_format('efi') returning EFIFS instance with object id 38
Dec 02 05:45:56 localhost-live org.fedoraproject.Anaconda.Modules.Storage[3141]: DEBUG:blivet: EFIFS.supported: supported: True ;

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I didn't see any cases of this on x86_64. I suspect there's a timing element to it. It looks like this is likely caused by:

const initializationMode = scenarios.find(sc => sc.id === storageScenarioId).initializationMode;

in src/hooks/Storage.jsx , but that code's been around for a while so I don't know why it started being a problem now...