Debut theme - added a second navigation menu, but its dropdowns don't work?

Store Design
2

As is often the case, by writing out the above and looking at it again I think I may have found the solution to my own issue – does anyone know if this has any undesirable side-effects?

I’ve modified theme.js and changed line 2893 from:

cache = {
      nav: navigation,
      topLevel: document.querySelectorAll(selectors.siteNavLinkMain),
      parents: navigation.querySelectorAll(selectors.siteNavHasDropdown),
      subMenuLinks: document.querySelectorAll(selectors.siteNavChildLinks),
      activeDropdown: document.querySelector(selectors.siteNavActiveDropdown),
      siteHeader: document.querySelector(selectors.siteHeader),
      siteNavChildLink: document.querySelectorAll(selectors.siteNavChildLink)
    };

to

cache = {
      nav: navigation,
      topLevel: document.querySelectorAll(selectors.siteNavLinkMain),
      parents: document.querySelectorAll(selectors.siteNavHasDropdown),	// was navigation -- 3dt 
      subMenuLinks: document.querySelectorAll(selectors.siteNavChildLinks),
      activeDropdown: document.querySelector(selectors.siteNavActiveDropdown),
      siteHeader: document.querySelector(selectors.siteHeader),
      siteNavChildLink: document.querySelectorAll(selectors.siteNavChildLink)
    };