Just return false if there is no connection.

If there is no connection and QtRO is build in debug mode it will assert,
if it build in release mode it will crash.

Change-Id: Icc528de233aa912c3b40acb84ac72ee9a24d62fb
Reviewed-by: Continuous Integration (KDAB) <build@kdab.com>
Reviewed-by: Brett Stottlemyer <bstottle@ford.com>