Use an empty dictionary for the 'this' scope when executing commands with Livestatus

fixes #9883

lib/livestatus/livestatusquery.cpp

@@ -635,6 +635,7 @@ void LivestatusQuery::ExecuteScriptHelper(const Stream::Ptr& stream)
 	try {
 		ScriptFrame frame;
 		frame.Locals = lsf.Locals;
+		frame.Self = lsf.Locals;
 		result = expr->Evaluate(frame);
 	} catch (const ScriptError& ex) {
 		delete expr;