Fix SWCommand with 0 args

Signed-off-by: Lixfel <git-5w3l@lixfel.de>

src/de/steamwar/command/SWCommand.java

@@ -83,7 +83,11 @@ public class SWCommand extends AbstractSWCommand<Chatter> {
 
             @Override
             public List<String> suggest(Invocation invocation) {
-                return SWCommand.this.tabComplete(Chatter.of(invocation.source()), invocation.alias(), invocation.arguments());
+                String[] args = invocation.arguments();
+                if(args.length == 0)
+                    args = new String[]{""};
+
+                return SWCommand.this.tabComplete(Chatter.of(invocation.source()), invocation.alias(), args);
             }
 
             @Override