Fix formatCommand to handle empty args correctly (#6213)

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### Details

**Proposed fix:**    
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Allows creating a clickable confirmation button for the clear command
message.
The space prevents the command from being executed properly, as this
tries to run `'/clear '` instead of `'/clear'`.

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OS: Linux

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Java version:  21

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- [ ] CraftBukkit 1.8.8


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---------

Co-authored-by: Josh Roy <[email protected]>
Co-authored-by: Copilot <[email protected]>

Author: 3 people

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

@@ -196,6 +196,9 @@ protected List<String> getTabCompleteOptions(final Server server, final CommandS
     }
 
     private String formatCommand(final String commandLabel, final String[] args) {
+        if (args == null || args.length == 0) {
+            return "/" + commandLabel;
+        }
         return "/" + commandLabel + " " + StringUtil.joinList(" ", (Object[]) args);
     }