Added null-check for lore

src/main/java/eu/ruekov/ruakij/LinkedBeaconTeleporters/linkedBeaconTeleporter/LinkedBeaconTeleporterManager.java

@@ -152,10 +152,12 @@ public class LinkedBeaconTeleporterManager {
     String serialiseBeaconItem(String name, List<String> lore){
         // get name and remove control-chars
         String str = name.replace("\\", "\\\\");
+        if(lore != null){
             for (String loreLine : lore) {
                 // get lore-lines and remove control-chars
                 str += "\n"+ loreLine.replace("\\", "\\\\");
             }
+        }
 
         return str;
     }