I keep having the same error so I added this

if (event.request.cache === 'only-if-cached' && event.request.mode !== 'same-origin')
return
And all errors are gone :-) meanbee/magento-meanbee-pwa#20 (comment)

cdn/pwabuilder-serviceworkers/1.1.1/serviceWorker2/src/pwabuilder-sw.fixed.js

@@ -39,6 +39,14 @@ self.addEventListener("fetch", function (event) {
 	};
 
 	event.waitUntil(updateCache(event.request));
+
+	/*!
+	 * https://github.com/meanbee/magento-meanbee-pwa/issues/20#issuecomment-497626347
+	 */
+
+	if (event.request.cache === "only-if-cached" && event.request.mode !== "same-origin") {
+		return;
+	}
 
 	event.respondWith(
 		fetch(event.request).catch (function (error) {

sw.js

@@ -40,6 +40,15 @@ self.addEventListener("fetch", function(event) {
 	};
 
 	event.waitUntil(updateCache(event.request));
+
+	/*!
+	 * https://github.com/meanbee/magento-meanbee-pwa/issues/20#issuecomment-497626347
+	 */
+
+	if (event.request.cache === "only-if-cached" && event.request.mode !== "same-origin") {
+		return;
+	}
+
 	event.respondWith(
 		fetch(event.request).catch(function(error) {
 			console.log(