Template annotations endpoint too strict in terms of JCR data and LM yaml definitions

Steps to reproduce

1.  Create page with https://git.magnolia-cms.com/projects/MODULES/repos/frontend-helpers/browse/samples/spa-react-minimal
2.  In Magnolia author check if the site does correctly the call to retrieve the template annotations and add components to areas
3. Remove secondary area from light module https://git.magnolia-cms.com/projects/MODULES/repos/frontend-helpers/browse/samples/spa-react-minimal/light-modules/sample-light-module/templates/pages/standard.yaml#25
4. In Magnolia author no longer we can edit anything

Expected results

Users can still modify all remaining areas

Actual results

Template annotations endpoint returns error:
code: "unknown"
message: "Area secondary is not defined in template definition of node /spa-home"
Preventing Magnolia from rendering green bars.

Workaround

Development notes