Directory: Don't attempt to access an uncached value

src/filesystem/common/CommonDirectory.cpp

@@ -61,7 +61,8 @@ std::shared_ptr<IDevice> CommonDirectory::device() const
     if ( m_device.isCached() == false )
     {
         auto d = m_fsFactory.createDeviceFromMrl( mrl() );
-        if( d != nullptr )
+        if( d == nullptr )
+            return nullptr;
         m_device = std::move( d );
     }
     return m_device.get();