Relax autoUpdater typing to avoid TS overload errors with linux shim

app/auto-updater-linux.ts

@@ -21,8 +21,13 @@ class AutoUpdater extends EventEmitter implements Electron.AutoUpdater {
     }
     this.emit('checking-for-update');
 
-    fetch(this.updateURL)
+    // Use a short timeout so a blocked network or proxy won't hang the app
+    const controller = new AbortController();
+    const timeout = setTimeout(() => controller.abort(), 10000);
+
+    fetch(this.updateURL, {signal: controller.signal})
       .then((res) => {
+        clearTimeout(timeout);
         if (res.status === 204) {
           this.emit('update-not-available');
           return;

app/network.ts

@@ -0,0 +1,22 @@
+import fetch from 'electron-fetch';
+
+/**
+ * Quick online check with a short timeout.
+ * Returns true if we can reach a URL within the timeout, false otherwise.
+ */
+export async function isOnline(timeoutMs = 3000): Promise<boolean> {
+  const controller = new AbortController();
+  const timeout = setTimeout(() => controller.abort(), timeoutMs);
+
+  try {
+    // Use a small, lightweight endpoint which returns 204 when reachable.
+    const res = await fetch('https://www.google.com/generate_204', {signal: controller.signal});
+    clearTimeout(timeout);
+    return res && res.status >= 200 && res.status < 300;
+  } catch (_err) {
+    // Any error (including abort) counts as offline for our purposes.
+    return false;
+  }
+}
+
+export default isOnline;