Launch emulator error message

Summary:
It's not obvious for non-mobile developers how to fix it when there are no emulators available. Adding a quick section in the troubleshooting guide and linking to it.

Changelog: Add link to troubleshooting page when no emulators are available.

Reviewed By: nikoant

Differential Revision: D36599925

fbshipit-source-id: f3a1e79e07209e34b66176102c85e7797292978c

desktop/flipper-ui-core/src/sandy-chrome/appinspect/LaunchEmulator.tsx

@@ -27,6 +27,7 @@ import {Provider} from 'react-redux';
 import {IOSDeviceParams} from 'flipper-common';
 import {getRenderHostInstance} from '../../RenderHost';
 import SettingsSheet from '../../chrome/SettingsSheet';
+import {Link} from '../../ui';
 
 const COLD_BOOT = 'cold-boot';
 
@@ -190,7 +191,16 @@ export const LaunchEmulatorDialog = withTrackingScope(
       <>
         {waitingForResults && <Spinner />}
         {!waitingForResults && items.length === 0 && (
-          <Alert message="No emulators available" />
+          <Alert
+            message={
+              <>
+                No emulators available. <br />
+                <Link href="http://fbflipper.com/docs/getting-started/troubleshooting/general/#i-see-no-emulators-available">
+                  Learn more
+                </Link>
+              </>
+            }
+          />
         )}
       </>
     );

desktop/flipper-ui-core/src/sandy-chrome/appinspect/__tests__/LaunchEmulator.spec.tsx

@@ -47,7 +47,14 @@ test('Can render and launch android apps - no emulators', async () => {
     <div
       class="ant-alert-message"
     >
-      No emulators available
+      No emulators available. 
+      <br />
+      <a
+        class="ant-typography"
+        href="http://fbflipper.com/docs/getting-started/troubleshooting/general/#i-see-no-emulators-available"
+      >
+        Learn more
+      </a>
     </div>
   `);
 });

docs/getting-started/troubleshooting/general.mdx

@@ -41,3 +41,13 @@ The following devices are known to be incompatible or face issues with Flipper:
 
 * Some Samsung devices ([Tracking Issue](https://github.com/facebook/flipper/issues/92)).
 * Genymotion emulators on Android 8+ are reported to have issues.
+
+## I see "No emulators available"
+
+For **Android**, you first need to set up Android Virtual Devices, called AVDs. You
+can do this in Android Studio using the [Virtual Device Manager](https://developer.android.com/studio/run/managing-avds).
+
+For **iOS**, after installing Xcode, you should have a default set of simulators set up. However,
+it is possible to delete them and there is no easy way to restore them afterwards. You can use
+[a script like this one](https://gist.github.com/dynamicguy/e8756a9f0f50af86d6e746d4b1ab6a09) to
+recreate the default set.