tz_now with empty tz panics

cbq> select now_tz('', 'TZD TZN TZF');

{

    "requestID": "3e3789a4-4504-4d16-8c39-e1b345c63d09",

    "signature": {

        "$1": "string"

    },

    "results": [

    ],

    "errors": [

        {

            "code": 5001,

            "msg": "Panic: runtime error: index out of range [0] with length 0"

        }

    ],

    "status": "aborted", 

2023-11-16T09:29:49.218-08:00 [SEVERE] request text: <ud>select now_tz('', 'TZD TZN TZF');</ud>

2023-11-16T09:29:49.218-08:00 [SEVERE] query context: <ud></ud>

2023-11-16T09:29:49.218-08:00 [SEVERE] stack: goroutine 24316 [running]:

github.com/couchbase/query/execution.(*Context).Recover(0xc00014ca80, 0xc000005500)

        /home/couchbase/jenkins/workspace/couchbase-server-unix/goproj/src/github.com/couchbase/query/execution/context.go:1704 +0x85

panic({0x2e898e0?, 0xc0005992a8?})

        /home/couchbase/.cbdepscache/exploded/x86_64/go-1.21.3/go/src/runtime/panic.go:914 +0x21f

github.com/couchbase/query/execution.(*InitialProject).RunOnce.(*base).runConsumer.func1.2()

        /home/couchbase/jenkins/workspace/couchbase-server-unix/goproj/src/github.com/couchbase/query/execution/base.go:983 +0x150

panic({0x2e898e0?, 0xc0005992a8?})

        /home/couchbase/.cbdepscache/exploded/x86_64/go-1.21.3/go/src/runtime/panic.go:914 +0x21f

github.com/couchbase/query/expression.gatherZone({0x0?, 0xc0000d98b8?}, 0x11b8a25?)

        /home/couchbase/jenkins/workspace/couchbase-server-unix/goproj/src/github.com/couchbase/query/expression/func_date.go:3941 +0xcc8

github.com/couchbase/query/expression.loadLocation({0x0?, 0x7f81a20d3460?})

...