firebase-module: Error registering workbox

Hi I get: Error registering workbox: TypeError: Cannot read property ‘addEventListener’ of undefined

workbox.js?8a5e:1 Error registering workbox: TypeError: Cannot read property 'addEventListener' of undefined at new Workbox (workbox-window.dev.es5.mjs?f82d:612) at _callee$ (workbox.js?8a5e:1) at tryCatch (runtime.js?96cf:63) at Generator.invoke [as _invoke] (runtime.js?96cf:293) at Generator.eval [as next] (runtime.js?96cf:118) at asyncGeneratorStep (asyncToGenerator.js?1c17:3) at _next (asyncToGenerator.js?1c17:25)

Do you need more info beyond that? Thanks Yalon