Do not segfault

upgradeoperation.cpp

@@ -38,8 +38,16 @@ UpgradeOperation::~UpgradeOperation()
 void UpgradeOperation::start(QList<APM::OperationName> operations, QHash<APM::OptionName, QStringList> options, QStringList args)
 {
     QList<Akabei::Package*> pkgs;
-    foreach (const QString &p, args)
-        pkgs << Akabei::Backend::instance()->loadPackageFromFile(p);
+    foreach (const QString &p, args) {
+        Akabei::Package * pkg = Akabei::Backend::instance()->loadPackageFromFile(p);
+        if (pkg)
+            pkgs << pkg;
+    }
+    
+    if (pkgs.isEmpty()) {
+        emit upgradeFinished();
+        return;
+    }
     
     QueueOperation *op = new QueueOperation(operations.first(), options, this);
     op->start(AkabeiClient::Install, pkgs);