Exception thrown if an object being modified doesn't exist yet.
For example, this exception should be thrown whenever there is an attempt to modify a database table, field, or index that does not currently exist in the database schema.
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https://api.drupal.org/api/drupal/core!lib!Drupal!Core!Database!SchemaObjectDoesNotExistException.php/class/SchemaObjectDoesNotExistException/8.1.x