Unable to edit text content of registered component

When using a custom component, I can’t seem to set any text content (dynamic text is allowed, however) - see video below:

Also getting the following error several times after editing text content on other code components.

This is how I'm registering my component
// Navigation
PLASMIC.registerComponent(BreadcrumbItem, {
  name: 'BreadcrumbItem',
  props: {
    key: 'string',
    elementType: 'string',
    isCurrent: 'boolean',
    isDisabled: 'boolean',
    children: 'slot',
  },
});

PLASMIC.registerComponent(Breadcrumbs, {
  name: 'Breadcrumbs',
  props: {
    className: 'string',
    children: {
      type: 'slot',
      allowedComponents: ['BreadcrumbItem'],
      defaultValue: [
        {
          type: 'component',
          name: 'BreadcrumbItem',
          props: {
            key: 'home',
            children: {
              type: 'text',
              value: 'Home',
            },
          },
        },
        {
          type: 'component',
          name: 'BreadcrumbItem',
          props: {
            key: 'store',
            children: {
              type: 'text',
              value: 'Store',
            },
          },
        },
      ],
    },
  },
});

Followed up here Slack