This is a testharness.js-based test.
Harness Error. harness_status.status = 1 , harness_status.message = Unhandled rejection: Failed to register a ServiceWorker for scope ('https://web-platform.test:8444/html/semantics/scripting-1/the-script-element/json-module/does/not/exist') with script ('https://web-platform.test:8444/html/semantics/scripting-1/the-script-element/json-module/non-object.tentative.any.worker.js'): ServiceWorker script evaluation failed
Harness: the test ran to completion.