Digests sometimes don't conform to Schema

[gjbunyea]

Occasionally, the toolkit will output a digest that is unable to be ingested due to not matching the Schema. A known case of this is

According to the Schema, all headings should be of this structure

   {
      "children": [
        {
          "children": [
            {
              "text": "A Great Title"
            }
          ],
          "id": "3191676082",
          "type": "h1"
        }
      ],
      "id": "88205506",
      "type": "content"
    },

The above error comes from an ingestion of this course: https://svn.oli.cmu.edu/svn/content/editor/projects/echo-oli-cmu-edu/interactive-jtkk2d6p/branches/v_1_0-echo
Changing the error in the above image from 'title' to 'h1' allowed this course to be ingested.

[gjbunyea]

Here are some additional examples of Invalid Schemas

The above errors stem from this digest:
c_at_cm_3-7.zip
user-images.githubusercontent.com/18299544/186006303-8add34aa-9925-40d7-b6c1-9c2c39395544.png)
Produced from this course: https://svn.oli.cmu.edu/svn/content/c_at_cm/c_at_cm/branches/v_3_7-echo