Revert "unroll first iteration of AsyncIterableIterator, get more explicit typing"
Revert "unroll first iteration of AsyncIterableIterator, get more explicit typing"

This reverts commit 762e66b6fcd95df170dd1f75fd0d8e5ffdc65d16.

slackapi/node-slack-sdk,slackapi/node-slack-sdk,slackapi/node-slack-sdk,slackapi/node-slack-sdk,slackhq/node-slack-client