Fix crash

app/src/leanback/java/com/fongmi/android/tv/ui/activity/LiveActivity.java

@@ -740,12 +740,14 @@ public class LiveActivity extends BaseActivity implements GroupPresenter.OnClick
     }
 
     private void prevLine() {
+        if (mChannel == null) return;
         mChannel.prevLine();
         showInfo();
         fetch();
     }
 
     private void nextLine(boolean show) {
+        if (mChannel == null) return;
         mChannel.nextLine();
         if (show) showInfo();
         else setInfo();

app/src/mobile/java/com/fongmi/android/tv/ui/activity/LiveActivity.java

@@ -834,12 +834,14 @@ public class LiveActivity extends BaseActivity implements CustomKeyDownLive.List
     }
 
     private void prevLine() {
+        if (mChannel == null) return;
         mChannel.prevLine();
         showInfo();
         fetch();
     }
 
     private void nextLine(boolean show) {
+        if (mChannel == null) return;
         mChannel.nextLine();
         if (show) showInfo();
         else setInfo();