After setting a value of a attribute in a custom widget I got a javascript error saying that I should first check the value using the mendix/validator. I added the mendix/validator to the widget (documented on https://apidocs.mendix.com/6/client/module-mendix_validator.html) as this: define([ "dojo/_base/declare", "mendix/validator", "mxui/widget/_WidgetBase", ... ], function (declare, validator, _WidgetBase, ... But this gives me an error in the build-report.txt (it is however working when I run locally): error(311) Missing dependency. module: BootstrapInputAddons/widget/BootstrapInputAddons; dependency: mendix/validator What am I doing wrong?