See https://cs.chromium.org/chromium/src/third_party/WebKit/LayoutTests/external/wpt/html/infrastructure/safe-passing-of-structured-data/shared-array-buffers/resources/serviceworker-failure.js?l=4

Comment from mek@:

"any relying on state is potentially fragile, since the SW can get killed in between. Ideally you'd call waitUntil on the event from which you set state and then resolve the promise you passed to that from the event where you do something with the state."