Fixed crash reported by play store

app/src/main/java/org/linphone/LinphoneManager.java

@@ -332,6 +332,8 @@ public class LinphoneManager implements SensorEventListener {
     }
 
     public static synchronized Core getCore() {
+        if (!LinphoneContext.isReady()) return null;
+
         if (getInstance().mExited) {
             // Can occur if the UI thread play a posted event but in the meantime the
             // LinphoneManager was destroyed

app/src/main/java/org/linphone/activities/MainActivity.java

@@ -419,7 +419,11 @@ public abstract class MainActivity extends LinphoneGenericActivity
         Intent intent = new Intent();
         intent.setAction(Intent.ACTION_MAIN).addCategory(Intent.CATEGORY_HOME);
         intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
+        try {
             startActivity(intent);
+        } catch (IllegalStateException ise) {
+            Log.e("[Main Activity] Can't start home activity: ", ise);
+        }
     }
 
     private void quit() {

app/src/main/java/org/linphone/call/CallStatsFragment.java

@@ -89,7 +89,11 @@ public class CallStatsFragment extends Fragment {
     @Override
     public void onPause() {
         super.onPause();
-        LinphoneManager.getCore().removeListener(mListener);
+
+        Core core = LinphoneManager.getCore();
+        if (core != null) {
+            core.removeListener(mListener);
+        }
     }
 
     public void setDrawer(DrawerLayout drawer, RelativeLayout content) {