Fix NPE when there are no default options

lib/android/app/src/main/java/com/reactnativenavigation/parse/LayoutFactory.java

 package com.reactnativenavigation.parse;
 
 import android.app.Activity;
+import android.support.annotation.NonNull;
+import android.support.annotation.RestrictTo;
 
 import com.facebook.react.ReactInstanceManager;
 import com.reactnativenavigation.presentation.BottomTabPresenter;
 import com.reactnativenavigation.presentation.SideMenuPresenter;
 import com.reactnativenavigation.presentation.StackPresenter;
 import com.reactnativenavigation.react.EventEmitter;
+import com.reactnativenavigation.utils.Assertions;
 import com.reactnativenavigation.utils.ImageLoader;
 import com.reactnativenavigation.utils.TypefaceLoader;
 import com.reactnativenavigation.viewcontrollers.ChildControllersRegistry;
 import static com.reactnativenavigation.parse.Options.parse;
 
 public class LayoutFactory {
-
 	private Activity activity;
     private ChildControllersRegistry childRegistry;
 	private final ReactInstanceManager reactInstanceManager;
     private EventEmitter eventEmitter;
     private Map<String, ExternalComponentCreator> externalComponentCreators;
-    private Options defaultOptions;
+    private @NonNull Options defaultOptions = new Options();
     private TypefaceLoader typefaceManager;
 
-    public void setDefaultOptions(Options defaultOptions) {
+    public void setDefaultOptions(@NonNull Options defaultOptions) {
+        Assertions.assertNotNull(defaultOptions);
         this.defaultOptions = defaultOptions;
     }
 
         }
         return new TopTabsController(activity, childRegistry, node.id, tabs, new TopTabsLayoutCreator(activity, tabs), parse(typefaceManager, node.getOptions()), new Presenter(activity, defaultOptions));
     }
+
+    @NonNull
+    @RestrictTo(RestrictTo.Scope.TESTS)
+    public Options getDefaultOptions() {
+        return defaultOptions;
+    }
 }

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

+package com.reactnativenavigation.utils;
+
+import javax.annotation.Nullable;
+
+public class Assertions {
+    public static void assertNotNull(@Nullable Object object) {
+        if (object == null) throw new AssertionError();
+    }
+}

lib/android/app/src/test/java/com/reactnativenavigation/utils/LayoutFactoryTest.java

+package com.reactnativenavigation.utils;
+
+import com.facebook.react.ReactInstanceManager;
+import com.reactnativenavigation.BaseTest;
+import com.reactnativenavigation.parse.LayoutFactory;
+import com.reactnativenavigation.parse.LayoutNode;
+
+import org.json.JSONException;
+import org.json.JSONObject;
+import org.junit.Test;
+
+import static org.assertj.core.api.Java6Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+
+public class LayoutFactoryTest extends BaseTest {
+    private LayoutFactory uut;
+
+    @Override
+    public void beforeEach() {
+        uut = new LayoutFactory(mock(ReactInstanceManager.class));
+    }
+
+    @Test
+    public void sanity() throws JSONException {
+        assertThat(uut.create(component())).isNotNull();
+    }
+
+    @Test
+    public void defaultOptionsAreNotNull() {
+        assertThat(uut.getDefaultOptions()).isNotNull();
+        boolean exceptionThrown = false;
+        try {
+            //noinspection ConstantConditions
+            uut.setDefaultOptions(null);
+        } catch (AssertionError error) {
+            exceptionThrown = true;
+        }
+        assertThat(exceptionThrown).isTrue();
+    }
+
+    private LayoutNode component() throws JSONException {
+        return new LayoutNode("Component1", LayoutNode.Type.Component, new JSONObject().put("name", "com.component"), null);
+    }
+}