Cancel sign change and interact if previous events are cancelled

This fixes that blocks get placed/items used when trying to auto-fill
 a shop sign and the sign is getting destroyed for some reason

src/main/java/com/Acrobot/ChestShop/Listeners/Block/SignCreate.java

@@ -48,6 +48,7 @@ public class SignCreate implements Listener {
         ChestShop.callEvent(preEvent);
 
         if (preEvent.getOutcome().shouldBreakSign()) {
+            event.setCancelled(true);
             signBlock.breakNaturally();
             return;
         }

src/main/java/com/Acrobot/ChestShop/Listeners/Player/PlayerInteract.java

@@ -113,6 +113,8 @@ public class PlayerInteract implements Listener {
                             sign.setLine(i, changeEvent.getLine(i));
                         }
                         sign.update();
+                    } else {
+                        event.setCancelled(true);
                     }
                 } else {
                     Messages.NO_ITEM_IN_HAND.sendWithPrefix(player);