Fix #632 Change the default settings to "useRtmConnect: true"

slack.coffee

@@ -9,9 +9,18 @@ exports.use = (robot) ->
     # reacts to only messages by insalled workspace users in a shared channel
     installedTeamOnly: process.env.INSTALLED_TEAM_ONLY?
   try
-    options.rtm = JSON.parse(process.env.HUBOT_SLACK_RTM_CLIENT_OPTS)
-  catch
+    options.rtm = JSON.parse(process.env.HUBOT_SLACK_RTM_CLIENT_OPTS or '{}')
+    unless options.rtm.useRtmConnect?
+      # The original way to connect to one of our oldest APIs is finally retiring.
+      # For existing apps, rtm.start will start behaving exactly like rtm.connect
+      # on September 20, 2022. Beginning November 30, 2021, newly created apps and integrations
+      # will only be able to use rtm.connect.
+      # https://api.slack.com/changelog/2021-10-rtm-start-to-stop
+      options.rtm.useRtmConnect = true
+  catch e
+    console.error(e)
   try
-    options.rtmStart = JSON.parse(process.env.HUBOT_SLACK_RTM_START_OPTS)
-  catch
+    options.rtmStart = JSON.parse(process.env.HUBOT_SLACK_RTM_START_OPTS or '{}')
+  catch e
+    console.error(e)
   new SlackBot robot, options