qemu: report error querying launch params for inactive guest
qemu: report error querying launch params for inactive guest

Querying launch params on a inactive guest currently triggers
a warning about the monitor being NULL.

https://bugzilla.redhat.com/show_bug.cgi?id=2030437

Reviewed-by: Peter Krempa <2cf5c04c61aa466e4a47bfedc747d17279c72ffc@redhat.com>
Signed-off-by: Daniel P. Berrangé <bb938cf255e055ff3507f2627d214e8e62118fcf@redhat.com>

crobinso/libvirt,olafhering/libvirt,zippy2/libvirt,libvirt/libvirt,jfehlig/libvirt,libvirt/libvirt,crobinso/libvirt,zippy2/libvirt,jfehlig/libvirt,libvirt/libvirt,zippy2/libvirt,zippy2/libvirt,libvirt/libvirt,olafhering/libvirt,crobinso/libvirt,olafhering/libvirt,olafhering/libvirt,jfehlig/libvirt,crobinso/libvirt,jfehlig/libvirt