refactor: remove null check in register.ts options.base

Inside registerServiceWorker, we were originally using the nullash coalescing
operator to check if options.base was null or undefined. However, I realized
this check is not necessary.

If you look at getOptions' return value, we return an object with a key "base"
which is of type "string". We get that value by calling resolveBase which always
returns a string.

As a result, we didn't need to check if options.base was null or undefined
because it never can be.

src/browser/register.ts

@@ -4,12 +4,12 @@ import "./pages/error.css"
 import "./pages/global.css"
 import "./pages/login.css"
 
-async function registerServiceWorker(): Promise<void> {
+export async function registerServiceWorker(): Promise<void> {
   const options = getOptions()
   const path = normalize(`${options.csStaticBase}/dist/serviceWorker.js`)
   try {
     await navigator.serviceWorker.register(path, {
-      scope: (options.base ?? "") + "/",
+      scope: options.base + "/",
     })
     console.log("[Service Worker] registered")
   } catch (error) {