I agree with Bartosz Dziewoński. However, after checking out the code, I think the reason why I need to change the RLQ push statements is due to the resources/src/mediawiki.base/mediawiki.base.js modifications in v1.32 stable.
window.RLQ = { push: function ( entry ) { if ( typeof entry === 'function' ) { entry(); } else { mw.loader.using( entry[ 0 ], entry[ 1 ] ); } } };
It seems hacky, but when using RLQ.push() and mw.loader.using in widgets I now have to use
RLQ.push([ [], function () { mw.loader.using('mymodule'); });
Otherwise mw.loader.using won't be defined as the anonymous function is executed instantly (why mw.using.loader is not available globally yet at this time I dont know for sure).