Expose the desktop version & auth token synchronously

Being able to wait once and then directly access this data
synchronously is much better than needing to async every possible
access to this data.

src/preload.ts

@@ -2,11 +2,29 @@ import { contextBridge, ipcRenderer } from 'electron';
 
 import type { ContextMenuDefinition } from './context-menu';
 
+// These are technically asynchronous, but they're so fast that
+// they're effectively sychronously available - this seems to
+// run before inline scripts in the page itself, let alone the
+// main app code. Nonetheless, to be safe the UI can wait for
+// the preload promise here to confirm it's definitely ready.
+let desktopVersion: string | undefined;
+let authToken: string | undefined;
+
+const preloadPromise = Promise.all([
+    ipcRenderer.invoke('get-desktop-version').then(result => {
+        desktopVersion = result;
+    }),
+    ipcRenderer.invoke('get-server-auth-token').then(result => {
+        authToken = result;
+    })
+]);
+
 contextBridge.exposeInMainWorld('desktopApi', {
-    desktopVersion: () =>
-        ipcRenderer.invoke('get-desktop-version'),
-    serverAuthToken: () =>
-        ipcRenderer.invoke('get-server-auth-token'),
+    waitUntilDesktopApiReady: () => preloadPromise.then(() => {}),
+
+    getDesktopVersion: () => desktopVersion,
+    getServerAuthToken: () => authToken,
+
     selectApplication: () =>
         ipcRenderer.invoke('select-application'),
     openContextMenu: (options: ContextMenuDefinition) =>