Upgrade to TypeScript 4.1

Summary:
allow-large-files

Upgrade to TypeScript 4.1

Reviewed By: nikoant

Differential Revision: D25122073

fbshipit-source-id: 7d2bc6f97595c825c9527b0c6ecab07698d5f981

desktop/app/src/devices/AndroidDevice.tsx

@@ -170,7 +170,7 @@ export default class AndroidDevice extends BaseDevice {
         (_) =>
           new Promise((resolve, reject) => {
             this.adb.pull(this.serial, recordingLocation).then((stream) => {
-              stream.on('end', resolve);
+              stream.on('end', resolve as () => void);
               stream.on('error', reject);
               stream.pipe(createWriteStream(destination));
             });

desktop/app/src/server.tsx

@@ -157,7 +157,7 @@ class Server extends EventEmitter {
               'server',
             );
             server.emit('listening', port);
-            resolve(rsServer);
+            resolve(rsServer!);
           });
         return transportServer;
       };

desktop/app/src/utils/promiseTimeout.tsx

@@ -60,7 +60,7 @@ export function showStatusUpdatesForDuration(
   removeStatusMessage: (payload: StatusMessageType) => void,
 ): void {
   showStatusUpdatesForPromise(
-    new Promise((resolve, _reject) => {
+    new Promise<void>((resolve, _reject) => {
       setTimeout(function () {
         resolve();
       }, duration);