When Lucene throws on an overly complex regex in the ESQL regex logic, we return that error directly to the user as a 5xx class error. This should be a 4xx class user ...
"type": "esql_illegal_argument_exception", "reason": "unknown physical plan node [OrderExec]", [2023-09-27T18:52:46,078][INFO ][o.e.x.e.a.RestEsqlQueryAction ...