npchighlight: Do not render 'null' names (#9093)

Fix names showing as null in the NPC highlight plugin

Fixes #9084

runelite-client/src/main/java/net/runelite/client/plugins/npchighlight/NpcSceneOverlay.java

@@ -173,7 +173,7 @@ public class NpcSceneOverlay extends Overlay
 				break;
 		}
 
-		if (config.drawNames())
+		if (config.drawNames() && actor.getName() != null)
 		{
 			String npcName = Text.removeTags(actor.getName());
 			Point textLocation = actor.getCanvasTextLocation(graphics, npcName, actor.getLogicalHeight() + 40);