cannot be used within addons: Cannot read property 'env' of undefined

[jonathanong]

Cannot read property 'env' of undefined
TypeError: Cannot read property 'env' of undefined
    at Class.included (/home/circleci/code/node_modules/ember-cli-rollbar/index.js:13:46)
    at addons.map.addon (/home/circleci/code/node_modules/ember-cli/lib/models/addon.js:383:34)
    at Array.map (<anonymous>)
    at Class.eachAddonInvoke (/home/circleci/code/node_modules/ember-cli/lib/models/addon.js:381:24)
    at Class.included (/home/circleci/code/node_modules/ember-cli/lib/models/addon.js:652:10)
    at Class.superWrapper [as included] (/home/circleci/code/node_modules/core-object/lib/assign-properties.js:34:20)
    at EmberAddon.<anonymous> (/home/circleci/code/node_modules/ember-cli/lib/broccoli/ember-app.js:527:17)
    at Array.filter (<anonymous>)
    at EmberAddon._notifyAddonIncluded (/home/circleci/code/node_modules/ember-cli/lib/broccoli/ember-app.js:524:47)
    at EmberAddon.EmberApp (/home/circleci/code/node_modules/ember-cli/lib/broccoli/ember-app.js:144:10)

seems like you should be using app instead of this.app

https://github.com/davewasmer/ember-cli-rollbar/blob/master/index.js#L13
https://github.com/damiencaselli/ember-cli-sentry/blob/master/index.js#L17
ember-cli/ember-cli#3718