Mock fixtures missing `field_data`

3) add tests 😄

Gonna check it ;)

Not reproduced on my side.

This is happening on preview only. If we use the command npm run preview for preview then front-end app crashes when I open the component list.

I have taken the latest pull on 0.x branch and on running the npm run start I am still facing this issue.

WRT tests: #3461435: End-to-end test that tests both the client (UI) and server landed!

I see that #6 is saying this is only happening when not using the Drupal back-end, but when using the mocks. But #3461435 is testing client+Drupal server, not client+mock server.

So … #3461435 doesn't help. But #3450308: Create an Open API spec for the current mock HTTP responses would have caught this … because the mocks do not include field_data, and the UI code expects it to. Previously, the back end was behind the mocks, now (since #3452512: Add component instance edit form to contextual panel) the mocks are behind the back end. We'll keep having this game of chasing each other until #3450308 lands.

That makes me fairly confident in stating that the current MR is only fixing the symptom, not the root cause. AFAICT this should instead be updating /ui/mocks/fixtures.

Am just started with experience builder so I might be wrong
I started looking into above mentioned issue and below are my findings

1. The above issue is caused due to incorrect fixture.
2. It's failing because layout fixture does not consist `type` property.
due to which keyedLayout is always empty.

Object.values(layout.children).map(item => {
    if (item.type && components[item.type]) {
      keyedLayout[item.uuid] = item
    }
    return true;
  })

3. Component fixture is not matching with endpoint response from `/xb-compnents`
const selectedComponentType = keyedLayout[selectedComponent].type || 'noop';
the above always results in null as keyedLayout is empty.

updating component fixture and layout fixture in below format resolve issue however if you click on nested components "slots" it throws an same error because they are not added to keyedLayout.
Component fixture

{
  "component_1": {
    "name": "Component 1",
    "id": "1"
  },

Layout fixture:

{
        "uuid": "43cd7aa4-0160-4787-a3af-baf44ff17a88",
        "children": [],
        "type": "component_1",
        "nodeType": "component"
      },

#3460952: Implement add button for top level item (section) fixed this.

#3450308: Create an Open API spec for the current mock HTTP responses is making sure this can never happen again.