In T279646, da.wikipedia community added too many templates to newcomer tasks configuration (via MediaWiki:NewcomerTasks.json). That partially broke newcomer tasks, since it didn't suggest any task at all.
This throws "Search request is longer than the maximum allowed length" error when running xxx.php, but I can't find that error in logstash, see https://logstash.wikimedia.org/goto/8d861102be2e1c28beea30cb7cb42992.
Log "Search request is longer than the maximum allowed length" errors to logstash, so we can monitor re-occurence of this type of errors.
This task will probably become void if T279722: Exempt keywords from query length restrictions is implemented.