clientui: fix restoring sidepanel when expanding sidebar

Closing and opening the sidebar when the side panel is collapsed
currently expands the side panel to the most recently opened panel,
even if it was collapsed at the time the sidebar was closed, and also
incorrectly doesn't set the nav button as selected.

This changes the behavior of expanding the sidebar to not open the side
panel if it was not opened at the time the sidebar was closed.

runelite-client/src/main/java/net/runelite/client/ui/ClientUI.java

@@ -211,6 +211,7 @@ public class ClientUI
 					currentButton.setSelected(false);
 					currentNavButton.setSelected(false);
 					currentButton = null;
+					currentNavButton = null;
 				}
 				else
 				{