refactor: move trackerUrls to its own file

src/components/Room/Room.tsx

@@ -4,6 +4,7 @@ import Box from '@mui/material/Box'
 import Divider from '@mui/material/Divider'
 
 import { rtcConfig } from 'config/rtcConfig'
+import { trackerUrls } from 'config/trackerUrls'
 import { ShellContext } from 'contexts/ShellContext'
 import { usePeerRoom, usePeerRoomAction } from 'hooks/usePeerRoom'
 import { PeerActions } from 'models/network'
@@ -34,9 +35,7 @@ export function Room({
   const peerRoom = usePeerRoom(
     {
       appId,
-      trackerUrls: process.env.REACT_APP_TRACKER_URL
+      trackerUrls,
-        ? [process.env.REACT_APP_TRACKER_URL]
-        : undefined,
       rtcConfig,
     },
     roomId

src/config/trackerUrls.ts

@@ -0,0 +1,25 @@
+let trackerUrls: string[] | undefined = [
+  // If you would like to host your own Chitchatter instance with alternative
+  // WebTorrent trackers to connect peers, add them to this array. This array
+  // gets provided to Trystero as the `trackerUrls` configuration option:
+  // https://github.com/dmotz/trystero#joinroomconfig-namespace
+  //
+  // See the default tracker list for examples of what to use:
+  // https://github.com/dmotz/trystero/blob/694f49974974cc9df8b621db09215d6df10fad09/src/torrent.js#L27-L33
+]
+
+// If a tracker URL has been provided via the REACT_APP_TRACKER_URL environment
+// variable, prioritize using it. This is mainly relevant for local development
+// when using the `npm run dev` script. If you are hosting your own Chitchatter
+// instance, consider populating the trackerUrls above instead.
+if (process.env.REACT_APP_TRACKER_URL) {
+  trackerUrls.unshift(process.env.REACT_APP_TRACKER_URL)
+}
+
+// If no tracker URL overrides have been provided, set trackerUrls to undefined
+// to allow Trystero to use the default list (linked above).
+if (!trackerUrls.length) {
+  trackerUrls = undefined
+}
+
+export { trackerUrls }