title: Getting an error in Indexing after migration in Magento 2.2.6
body: <p>Product Categories indexer process unknown error:
  SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry '10-30' for key 'PRIMARY', query was: INSERT  INTO <code>temp_catalog_category_tree_index_1381a75b</code> (<code>parent_id</code>,<code>child_id</code>) VALUES (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?), (?, ?),
  <a href="https://i.stack.imgur.com/XQnfi.png" rel="nofollow noreferrer">Error Image</a></p>