Try to avoid coredumping if zrpc object doesn't exist, which can happen if backend server is misbehaving

src/controller.cpp

@@ -1987,7 +1987,7 @@ void Controller::refreshHUSHPrice()
 void Controller::shutdownhushd() 
 {
     // Save the wallet and exit the lightclient library cleanly.
-    if (zrpc->haveConnection()) 
+    if (zrpc && zrpc->haveConnection()) 
     {
         QDialog d(main);
         Ui_ConnectionDialog connD;
@@ -2010,7 +2010,7 @@ void Controller::shutdownhushd()
         connD.topIcon->setMovie(movie1);
         movie1->start();
         connD.status->setText(QObject::tr("Please wait for SilentDragonLite to exit"));
-        connD.statusDetail->setText(QObject::tr("Waiting for hushd to exit"));
+        connD.statusDetail->setText(QObject::tr("Please wait for SilentDragonLite to exit"));
     }
       
         bool finished = false;
@@ -2018,10 +2018,13 @@ void Controller::shutdownhushd()
             if (!finished)
                 d.accept();
             finished = true;
+            qDebug() << "saveWallet during shutdownhushd";
         });
 
         if (!finished)
             d.exec();
+    } else {
+        qDebug() << "No zrpc object, unclean shutdown and unable to call saveWallet!";
     }
 }