TunnelEditorFragment: do not pass null localConfig

Otherwise we might dereference it, per this play store gathered trace:

Xiaomi Redmi 3S (land), 2048MB RAM, Android 7.1
java.lang.NullPointerException:
  at com.wireguard.android.model.Tunnel.setConfig (Tunnel.java:118)
  at com.wireguard.android.fragment.TunnelEditorFragment.onOptionsItemSelected (TunnelEditorFragment.java:160)
  at android.app.Fragment.performOptionsItemSelected (Fragment.java:2478)
  at android.app.FragmentManagerImpl.dispatchOptionsItemSelected (FragmentManager.java:2182)
  at android.app.FragmentController.dispatchOptionsItemSelected (FragmentController.java:336)
  at android.app.Activity.onMenuItemSelected (Activity.java:3211)
  at com.android.internal.policy.PhoneWindow.onMenuItemSelected (PhoneWindow.java:1219)
  at com.android.internal.view.menu.MenuBuilder.dispatchMenuItemSelected (MenuBuilder.java:761)
  at com.android.internal.view.menu.MenuItemImpl.invoke (MenuItemImpl.java:152)
  at com.android.internal.view.menu.MenuBuilder.performItemAction (MenuBuilder.java:904)
  at com.android.internal.view.menu.MenuBuilder.performItemAction (MenuBuilder.java:894)
  at android.widget.ActionMenuView.invokeItem (ActionMenuView.java:616)
  at com.android.internal.view.menu.ActionMenuItemView.onClick (ActionMenuItemView.java:152)
  at android.view.View.performClick (View.java:5637)
  at android.view.View$PerformClick.run (View.java:22433)
  at android.os.Handler.handleCallback (Handler.java:751)
  at android.os.Handler.dispatchMessage (Handler.java:95)
  at android.os.Looper.loop (Looper.java:153)
  at android.app.ActivityThread.main (ActivityThread.java:6244)
  at java.lang.reflect.Method.invoke (Native Method)
  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run (ZygoteInit.java:891)
  at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:781)

1 files changed, 7 insertions, 6 deletions

diff --git a/app/src/main/java/com/wireguard/android/fragment/TunnelEditorFragment.java b/app/src/main/java/com/wireguard/android/fragment/TunnelEditorFragment.java
index eec5c098..aa4321e8 100644
--- a/app/src/main/java/com/wireguard/android/fragment/TunnelEditorFragment.java
+++ b/app/src/main/java/com/wireguard/android/fragment/TunnelEditorFragment.java
@@ -146,18 +146,19 @@ public class TunnelEditorFragment extends BaseFragment {
     public boolean onOptionsItemSelected(final MenuItem item) {
         switch (item.getItemId()) {
             case R.id.menu_action_save:
-                if (getSelectedTunnel() == null) {
+                final Tunnel selectedTunnel = getSelectedTunnel();
+                if (selectedTunnel == null) {
                     Log.d(TAG, "Attempting to create new tunnel " + localName.get());
                     final TunnelManager manager = Application.getComponent().getTunnelManager();
                     manager.create(localName.get(), localConfig)
                             .whenComplete(this::onTunnelCreated);
-                } else if (!getSelectedTunnel().getName().equals(localName.get())) {
+                } else if (!selectedTunnel.getName().equals(localName.get())) {
                     Log.d(TAG, "Attempting to rename tunnel to " + localName.get());
-                    getSelectedTunnel().rename(localName.get())
+                    selectedTunnel.rename(localName.get())
                             .whenComplete(this::onTunnelRenamed);
-                } else {
-                    Log.d(TAG, "Attempting to save config of " + getSelectedTunnel().getName());
-                    getSelectedTunnel().setConfig(localConfig)
+                } else if (localConfig != null) {
+                    Log.d(TAG, "Attempting to save config of " + selectedTunnel.getName());
+                    selectedTunnel.setConfig(localConfig)
                             .whenComplete(this::onConfigSaved);
                 }
                 return true;