Catch occasional NPE when setting tray icon.

src/main/java/org/qortal/gui/SysTray.java

@@ -291,6 +291,7 @@ public class SysTray {
 
 	public void setTrayIcon(int iconid) {
 		if (trayIcon != null) {
+			try {
 				switch (iconid) {
 					case 1:
 						this.trayIcon.setImage(Gui.loadImage("icons/qortal_ui_tray_syncing_time-alt.png"));
@@ -305,6 +306,9 @@ public class SysTray {
 						this.trayIcon.setImage(Gui.loadImage("icons/qortal_ui_tray_synced.png"));
 						break;
 				}
+			} catch (NullPointerException e) {
+				LOGGER.info("Unable to set tray icon");
+			}
 		}
 	}