avoid NPE in CLI mode (boardInfo not yet initialized)

Author: facchinm

arduino-core/src/processing/app/BaseNoGui.java

@@ -1122,7 +1122,9 @@ static public void selectBoard(TargetBoard targetBoard) {
   public static void selectSerialPort(String port) {
     PreferencesData.set("serial.port", port);
     BoardPort boardPort = getDiscoveryManager().find(port, true);
-    PreferencesData.set("serial.port.iserial", boardPort.getPrefs().get("iserial"));
+    if (boardPort != null) {
+      PreferencesData.set("serial.port.iserial", boardPort.getPrefs().get("iserial"));
+    }
     String portFile = port;
     if (port.startsWith("/dev/")) {
       portFile = portFile.substring(5);