Ensure computers work on centcom or when only one zlevel is accessible.

code/modules/nano/modules/crew_monitor.dm

@@ -33,6 +33,8 @@
 		ui.add_template("mapContent", "crew_monitor_map_content.tmpl")
 		// adding a template with the key "mapHeader" replaces the map header content
 		ui.add_template("mapHeader", "crew_monitor_map_header.tmpl")
+		if(!(ui.map_z_level in data["map_levels"]))
+			ui.set_map_z_level(data["map_levels"][1])
 
 		ui.set_initial_data(data)
 		ui.open()