packager edge case fix

lib/android/app/src/main/java/com/reactnativenavigation/NavigationApplication.java

@@ -1,6 +1,7 @@
 package com.reactnativenavigation;
 
 import android.app.Application;
+import android.content.Context;
 
 import com.facebook.react.ReactApplication;
 import com.facebook.react.ReactNativeHost;
@@ -8,11 +9,13 @@ import com.reactnativenavigation.react.ReactGateway;
 
 public abstract class NavigationApplication extends Application implements ReactApplication {
 
+	public static Context context;
 	private ReactGateway reactGateway;
 
 	@Override
 	public void onCreate() {
 		super.onCreate();
+		context = this;
 		reactGateway = new ReactGateway(this, isDebug());
 	}
 

lib/android/app/src/main/java/com/reactnativenavigation/react/NavigationReactInitializer.java

@@ -2,17 +2,23 @@ package com.reactnativenavigation.react;
 
 import com.facebook.react.ReactInstanceManager;
 import com.facebook.react.bridge.ReactContext;
+import com.facebook.react.devsupport.interfaces.PackagerStatusCallback;
 import com.reactnativenavigation.NavigationActivity;
+import com.reactnativenavigation.utils.Toaster;
+import com.reactnativenavigation.utils.UiThread;
 
 public class NavigationReactInitializer implements ReactInstanceManager.ReactInstanceEventListener {
 
 	private final ReactInstanceManager reactInstanceManager;
 	private final DevPermissionRequest devPermissionRequest;
+	private final boolean isDebug;
 	private boolean waitingForAppLaunchEvent = true;
+	private boolean isPackagerRunning = false;
 
 	public NavigationReactInitializer(ReactInstanceManager reactInstanceManager, boolean isDebug) {
 		this.reactInstanceManager = reactInstanceManager;
 		this.devPermissionRequest = new DevPermissionRequest(isDebug);
+		this.isDebug = isDebug;
 	}
 
 	public void onActivityCreated(NavigationActivity activity) {
@@ -42,6 +48,25 @@ public class NavigationReactInitializer implements ReactInstanceManager.ReactIns
 	}
 
 	private void prepareReactApp() {
+		if (isDebug && !isPackagerRunning) {
+			reactInstanceManager.getDevSupportManager().isPackagerRunning(new PackagerStatusCallback() {
+				@Override
+				public void onPackagerStatusFetched(final boolean packagerIsRunning) {
+					UiThread.post(new Runnable() {
+						@Override
+						public void run() {
+							isPackagerRunning = packagerIsRunning;
+							if (!isPackagerRunning) {
+								Toaster.toast("Packager is not running!");
+							} else {
+								prepareReactApp();
+							}
+						}
+					});
+				}
+			});
+			return;
+		}
 		reactInstanceManager.addReactInstanceEventListener(this);
 		if (shouldCreateContext()) {
 			reactInstanceManager.createReactContextInBackground();

lib/android/app/src/main/java/com/reactnativenavigation/utils/Toaster.java

@@ -0,0 +1,11 @@
+package com.reactnativenavigation.utils;
+
+import android.widget.Toast;
+
+import com.reactnativenavigation.NavigationApplication;
+
+public class Toaster {
+	public static void toast(String text) {
+		Toast.makeText(NavigationApplication.context, text, Toast.LENGTH_LONG).show();
+	}
+}