Load scripts in the head AND bottom of the page? I need to load head.js in my head and application.js at the bottom of my page. The following seems to stop all my scripts being loaded! Is there a syntax error? Im confused as I used the documentation from here:

https://www.drupal.org/docs/8/theming-drupal-8/adding-stylesheets-css-and-javascript-js-to-a-drupal-8-theme 

global:
  version: 1.x
  css:
    base:
      /ui/style.css: {preprocess: false, minified: false}

  js-header:
    header: true
    js:
      /ui/head.js: {preprocess: false, minified: false, weight: '-100'}

  js-footer:
    js:
      /ui/application.js: {preprocess: false, minified: false, weight: '-99'}


UPDATE - It appears to me that header: true is used to move either all or none of the scripts to the head. Can someone confirm if this is right? 

If this is the case, how can I load scripts in both the head and the bottom of the page?
You have to add additional libraries: https://ffwagency.com/blog/managing-css-and-javascript-files-drupal-8-libraries

So in my theme.info.yaml 

libraries:
  - THEME-NAME/global
  - THEME-NAME/custom


In my theme.libraries.yaml file:

global:
  version: 1.x
  css:
    base:
      /ui/style.css: {preprocess: false, minified: false}
  js:
    /ui/application.js: {preprocess: false, minified: false, weight: '-99'}

custom:
  version: 1.x
  header: true
  js:
    /ui/head.js: {}