_setInvalidState() {
        if (this.isInputElement) {
            AutoNumericHelper.setInvalidState(this.domElement);
        } else {
            this._addCSSClass(this.settings.invalidClass);
        }

        this._triggerEvent(AutoNumeric.events.invalidValue, this.domElement);
        this.validState = false;
    }
Set the invalid state on the AutoNumeric element.
If the element is not an input, and therefore a contenteditable-enabled element, its validity state cannot be changed.
In that case, the invalid css class defined with the `settings.invalidClass` option is added to the element.
The 'autoNumeric:invalidValue' event is always sent when this function is called.

@private