Live error checking as you type on editor if chosen previous sibling is not a child of the selected parent article

Current failure behavior if use submits anyways is: shows API error previousSiblingId "@cirosantilli/physics" does not exist, is not a header or is not a child of parentId "@cirosantilli/test-article" under title, and it only goes away if you edit title, which is confusing as it is not title related. Also, while title error is visible, the submit button is inactive so the user is left a bit stuck.