```coffeescript
logger = require("logger-sharelatex")
NotificationsHandler = require("./NotificationsHandler")

module.exports =

	# Note: notification keys should be url-safe

	groupPlan: (user, licence)->
		key : "join-sub-#{licence.subscription_id}"
		create: (callback = ->)->
			messageOpts =
				groupName: licence.name
				subscription_id: licence.subscription_id
			logger.log user_id:user._id, key:key, "creating notification key for user"
			NotificationsHandler.createNotification user._id, @key, "notification_group_invite", messageOpts, null, callback

		read: (callback = ->)->
			NotificationsHandler.markAsReadWithKey user._id, @key, callback

	projectInvite: (invite, project, sendingUser, user) ->
		key: "project-invite-#{invite._id}"
		create: (callback=()->) ->
			messageOpts =
				userName: sendingUser.first_name
				projectName: project.name
				projectId: project._id.toString()
				token: invite.token
			logger.log {user_id: user._id, project_id: project._id, invite_id: invite._id, key: @key}, "creating project invite notification for user"
			NotificationsHandler.createNotification user._id, @key, "notification_project_invite", messageOpts, invite.expires, callback
		read:  (callback=()->) ->
			NotificationsHandler.markAsReadByKeyOnly @key, callback
```

Fix reference to `@key` in log expression.
user
```coffeescript
logger = require("logger-sharelatex")
NotificationsHandler = require("./NotificationsHandler")

module.exports =

	# Note: notification keys should be url-safe

	groupPlan: (user, licence)->
		key : "join-sub-#{licence.subscription_id}"
		create: (callback = ->)->
			messageOpts =
				groupName: licence.name
				subscription_id: licence.subscription_id
			logger.log user_id:user._id, key: @key, "creating notification key for user"
			NotificationsHandler.createNotification user._id, @key, "notification_group_invite", messageOpts, null, callback

		read: (callback = ->)->
			NotificationsHandler.markAsReadWithKey user._id, @key, callback

	projectInvite: (invite, project, sendingUser, user) ->
		key: "project-invite-#{invite._id}"
		create: (callback=()->) ->
			messageOpts =
				userName: sendingUser.first_name
				projectName: project.name
				projectId: project._id.toString()
				token: invite.token
			logger.log {user_id: user._id, project_id: project._id, invite_id: invite._id, key: @key}, "creating project invite notification for user"
			NotificationsHandler.createNotification user._id, @key, "notification_project_invite", messageOpts, invite.expires, callback
		read:  (callback=()->) ->
			NotificationsHandler.markAsReadByKeyOnly @key, callback
```
assistant