fix: fix favicon

src/service-worker.js

@@ -28,7 +28,7 @@ const ON_DEMAND_CACHE = [
     cache: WEBPACK_ASSETS
   },
   {
-    regex: /icon-.*?\.png/,
+    regex: /\/icon-.*?\.png/,
     cache: ASSETS
   }
 ]
@@ -41,7 +41,7 @@ const assets = __assets__
   .filter(filename => !filename.endsWith('.webapp')) // KaiOS manifest
   .filter(filename => !/emoji-.*?\.json$/.test(filename)) // useless to cache; it already goes in IndexedDB
   .filter(filename => !/screenshot-.*?\.png/.test(filename)) // only used during PWA installation, don't bother caching
-  .filter(filename => !/icon-.*?\.png/.test(filename)) // cache app icons on-demand
+  .filter(filename => !/\/icon-.*?\.png/.test(filename)) // cache app icons on-demand (but not favicon)
 
 // `shell` is an array of all the files generated by webpack
 // also contains '/index.html' for some reason