QmlDesigner: crash fix

ModelNode::isComponent() is throwing an exception if the node is
not valid.

Change-Id: I4b34b9a583108923d584a73585f3001df68a741d
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
FakeVim: Fix Vk command

Fixes visual representation (selection exported to editor widget) of
"Vk" command on empty line.

Change-Id: Iac5fabe53a65d7b94d0a1ed02aff3a7b3804a37b
Reviewed-by: hjk <hjk121@nokiamail.com>