Fix error when running /helpop from console (#6385)

Fixes #6342

---------

Co-authored-by: Josh Roy <10731363+JRoy@users.noreply.github.com>

Author: benniofficialdev

Essentials/src/main/java/com/earth2me/essentials/commands/Commandhelpop.java

@@ -51,9 +51,11 @@ private void sendMessage(final IMessageRecipient from, final String[] args) thro
         final HelpopMessageSendEvent sendEvent = new HelpopMessageSendEvent(from, recipients, message);
         ess.getServer().getPluginManager().callEvent(sendEvent);
 
-        final IUser sender = (IUser) from;
-        if(!recipients.contains(sender)){
-            from.sendTl("helpOp", from.getDisplayName(), message);
+        if (from instanceof IUser) {
+            final IUser sender = (IUser) from;
+            if (!recipients.contains(sender)) {
+                from.sendTl("helpOp", from.getDisplayName(), message);
+            }
         }
 
         for (IUser recipient : sendEvent.getRecipients()) {