Insert panel preview is not working for sections

The section previews are actually rendering correctly but are being pushed outside of the tooltip by "undefined" text which was the preview trying to include the css/js header/js footer. css, js_header, and js_footer weren't defined in the component definition which caused the include statements to ultimately be 'undefined' instead of an html string.

{
  "id": "fakeSection2",
  "name": "Fake Section 2",
  "layoutModel": {
    "layout": {
      "nodeType": "root",
      "name": "root",
      "uuid": "root",
      "children": [
        {
          "uuid": "abcde",
          "nodeType": "component",
          "type": "experience_builder:two_column",
          "children": [
            {
              "uuid": "two-column-uuid-slot-column_one",
              "name": "column_one",
              "nodeType": "slot",
              "children": [
                {
                  "uuid": "fghij",
                  "nodeType": "component",
                  "type": "experience_builder:my-hero",
                  "children": []
                }
              ]
            },
            {
              "uuid": "two-column-uuid-slot-column_two",
              "name": "column_two",
              "nodeType": "slot",
              "children": [
                {
                  "uuid": "klmno",
                  "nodeType": "component",
                  "type": "experience_builder:my-hero",
                  "children": []
                }
              ]
            }
          ]
        }
      ]
    },
    "model": {
      "abcde": {
        "width": 50,
        "name": "Two column"
      },
      "fghij": {
        "heading": "A hero in slot 1!",
        "subheading": "This text was defined in the section.",
        "cta1": "Yes",
        "cta2": "No",
        "cta1href": "https://drupal.org",
        "cta2href": "https://google.com",
        "name": "Hero"
      },
      "klmno": {
        "heading": "A hero in slot 2!",
        "subheading": "Text saved in the section",
        "cta1": "Up",
        "cta2": "Down",
        "cta1href": "https://drupal.org",
        "cta2href": "https://google.com",
        "name": "Hero"
      }
    }
  },
  "default_markup": "<h1 style=\"background: black; color: white;\">TODO</h1>"
}

Good find @ctrladel ! Fortunately, I don't think we need to make the css, js_header, and js_footer properties "optional" because these properties are guaranteed to be present in a Drupal-provided component list. The issue here was the dummy data in sections.ts was incomplete so updating just that should be sufficient.

I've merged in the change to fix the "fake sections" preview. @lauriii I'm not sure if this issue should remain open until the actual real implementation of sections is complete or if you are happy that it will be address as part of that work ( 📌 Allow saving component compositions as sections Postponed )

Let's close this one. We can deal with the rest in 📌 Allow saving component compositions as sections Postponed / follow-ups to that.

crediting shyam_bhatt (to match the commit) and jessebaker for code and review and lauri for reporting

Automatically closed - issue fixed for 2 weeks with no activity.