Uncaught SyntaxError: Unexpected token ‘<', "<!DOCTYPE ".

 sendHitRequest: async function() {
        try {
            var t = this.getRequestUrl("hit")
              , i = new URLSearchParams({
                ...WP_Statistics_Tracker_Object.hitParams,
                referred: this.getReferred(),
                page_uri: this.getPathAndQueryString()
            }).toString();
            let e = new XMLHttpRequest;
            e.open("POST", t, !0),
            e.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"),
            e.send(i),
            e.onreadystatechange = function() {
                var t;
                4 === e.readyState && (200 === e.status ? (t = JSON.parse(e.responseText),
                this.hitRequestSuccessful = !1 !== t.status) : (this.hitRequestSuccessful = !1,
                console.warn("WP Statistics: Hit request failed with status " + e.status)))
            }
            .bind(this)
        } catch (t) {
            this.hitRequestSuccessful = !1,
            console.error("WP Statistics: Error sending hit request:", t)
        }
    },

in

 4 === e.readyState && (200 === e.status ? (t = JSON.parse(e.responseText),