Deploy hook: `TypeError: Subscriptions.subscriptions is not a function`

[gingerhendrix]

018-09-20T11:13:39.573086+00:00 heroku[router]: at=info method=POST path="/hubot/semaphore-events/deploy" host=hubot-textmaster.herokuapp.com request_id=42d05c8f-2feb-46ac-afcc-20c6123b3839 fwd="35.199.44.164" dyno=web.1 connect=1ms service=8ms status=200 bytes=199 protocol=https
2018-09-20T11:13:40.046066+00:00 app[web.1]: (node:4) UnhandledPromiseRejectionWarning: TypeError: Subscriptions.subscriptions is not a function
2018-09-20T11:13:40.046080+00:00 app[web.1]: at lookupNamesFromSubscriptions (/app/scripts/notify_on_deployments.js:65:33)
2018-09-20T11:13:40.046082+00:00 app[web.1]: at Function._.map._.collect (/app/node_modules/underscore/underscore.js:205:24)
2018-09-20T11:13:40.046084+00:00 app[web.1]: at _.(anonymous function) [as map] (/app/node_modules/underscore/underscore.js:1639:39)
2018-09-20T11:13:40.046086+00:00 app[web.1]: at buildNotificationsMessage (/app/scripts/notify_on_deployments.js:70:8)
2018-09-20T11:13:40.046088+00:00 app[web.1]: at buildMessage (/app/scripts/notify_on_deployments.js:95:19)
2018-09-20T11:13:40.046090+00:00 app[web.1]: at notify (/app/scripts/notify_on_deployments.js:101:21)
2018-09-20T11:13:40.046092+00:00 app[web.1]: at EventEmitter.robot.on (/app/scripts/notify_on_deployments.js:126:7)
2018-09-20T11:13:40.046093+00:00 app[web.1]: at process._tickCallback (internal/process/next_tick.js:68:7)