mem leak in connect

[jonnymacs]

There is a memory leak caused by ElasticsearchClient.connect. The error closure holds a reference to the client that creates a circular reference such that the client is never deallocated.

removing the error closure resolves the memory leak, but I'm not sure the best way to resolve. This is working for me, and I can submit a PR if there are no other recommendations.

Steps to reproduce

Interact with elastic search while running xcode profiling instruments. Run generations to see the memory grow unbounded.

Expected behavior

client is deallocated

Actual behavior

Environment

• Version/commit of the Elasticsearch client you are using
  latest

• Version of Elasticsearch that you are using
  6.5

• Vapor Framework version:
  3.x