Error: Uncaught (in promise): SyntaxError: JSON.parse: unexpected character at line 1 column 2 of the JSON data

here is the function in main.js which it is pointing to.--

HomePage.prototype.loadCheckbook = function (account) {
        var _this = this;
        this.store.get(account).then(function (data) {
            _this.register = JSON.parse(data) || [];
            console.log("Updating..");
        });
    };