Where running the command bin/console doctrine:mongodb:schema:drop in DoctrineMongoDBODMBundle on a non-atlas cluster, the following error is returned:

Using Atlas Search Database Commands and the $listSearchIndexes aggregation stage requires additional configuration. Please connect to Atlas or an AtlasCLI local deployment to enable. For more information on how to connect, see https://dochub.mongodb.org/core/atlas-cli-deploy-local-reqs.

It should be skipped: if the $listSearchIndexes operation is not available, we know there is no search index to delete.