Fix 2 bugs

[eshraao]

I have a NullPointerException when I remove an AbstractBorder containing a component that has the focus :

Panel root = new Panel();
Button button = new Button("test", root::removeAllComponents);
button.withBorder(Borders.singleLine()).addTo(root);
setComponent(root);

A VerticalLinearLayout displays nothing when the Panel has a row size of 1 and two components are added to it :

Panel root = new Panel();
Panel panel = new Panel().addTo(root);
panel.setPreferredSize(new TerminalSize(10, 1));
new Label("test1").addTo(panel);
new Label("test2").addTo(panel);

[mabe02]

Thank you!