ember-simple-auth: Deployment using the current master fails with SyntaxError

I used the current master of this package in my project, and everything was fine until it tried to deploy.

- build failed
Error: The Broccoli Plugin: [Fingerprint] failed with:
SyntaxError: Unexpected token: punc (.)
    at JS_Parse_Error.get (eval at <anonymous> (/home/ubuntu/supertaster/node_modules/uglify-js/tools/node.js:27:1), <anonymous>:86:23)
    at new BroccoliBuildError (/home/ubuntu/supertaster/node_modules/broccoli-builder/lib/broccoli-build-error.js:18:29)
    at /home/ubuntu/supertaster/node_modules/broccoli-builder/lib/builder.js:168:19
    at tryCatch (/home/ubuntu/supertaster/node_modules/rsvp/dist/rsvp.js:525:12)
    at invokeCallback (/home/ubuntu/supertaster/node_modules/rsvp/dist/rsvp.js:538:13)
    at publish (/home/ubuntu/supertaster/node_modules/rsvp/dist/rsvp.js:508:7)
    at publishRejection (/home/ubuntu/supertaster/node_modules/rsvp/dist/rsvp.js:443:3)
    at flush (/home/ubuntu/supertaster/node_modules/rsvp/dist/rsvp.js:2415:5)
    at _combinedTickCallback (internal/process/next_tick.js:73:7)
    at process._tickDomainCallback (internal/process/next_tick.js:128:9)

The broccoli plugin was instantiated at: 
    at Fingerprint.Plugin (/home/ubuntu/supertaster/node_modules/broccoli-plugin/index.js:7:31)
    at Fingerprint.Filter [as constructor] (/home/ubuntu/supertaster/node_modules/broccoli-filter/index.js:34:10)
    at new Fingerprint (/home/ubuntu/supertaster/node_modules/broccoli-asset-rev/lib/fingerprint.js:21:10)
    at Fingerprint (/home/ubuntu/supertaster/node_modules/broccoli-asset-rev/lib/fingerprint.js:16:12)
    at new AssetRev (/home/ubuntu/supertaster/node_modules/broccoli-asset-rev/lib/asset-rev.js:31:25)
    at AssetRev (/home/ubuntu/supertaster/node_modules/broccoli-asset-rev/lib/asset-rev.js:7:12)
    at Class.postprocessTree (/home/ubuntu/supertaster/node_modules/broccoli-asset-rev/index.js:31:40)
    at projectOrAddon.addons.reduce (/home/ubuntu/supertaster/node_modules/ember-cli/lib/utilities/addon-process-tree.js:6:25)
    at Array.reduce (native)
    at addonProcessTree (/home/ubuntu/supertaster/node_modules/ember-cli/lib/utilities/addon-process-tree.js:4:32)
    at EmberApp.addonPostprocessTree (/home/ubuntu/supertaster/node_modules/ember-cli/lib/broccoli/ember-app.js:598:12)
    at EmberApp.toTree (/home/ubuntu/supertaster/node_modules/ember-cli/lib/broccoli/ember-app.js:1701:17)
    at emberCliBuilds (/home/ubuntu/supertaster/ember-cli-build.js:29:14)
    at Builder.setupBroccoliBuilder (/home/ubuntu/supertaster/node_modules/ember-cli/lib/models/builder.js:56:19)
    at new Builder (/home/ubuntu/supertaster/node_modules/ember-cli/lib/models/builder.js:30:10)
    at CoreObject.build (/home/ubuntu/supertaster/node_modules/ember-cli-deploy-build/index.js:26:23)
    at Object.fn (/home/ubuntu/supertaster/node_modules/ember-cli-deploy/lib/tasks/pipeline.js:93:21)
    at Pipeline._notifyPipelinePluginHookExecution (/home/ubuntu/supertaster/node_modules/ember-cli-deploy/lib/models/pipeline.js:173:19)
    at tryCatch (/home/ubuntu/supertaster/node_modules/rsvp/dist/rsvp.js:525:12)
    at invokeCallback (/home/ubuntu/supertaster/node_modules/rsvp/dist/rsvp.js:538:13)
    at /home/ubuntu/supertaster/node_modules/rsvp/dist/rsvp.js:606:14
    at flush (/home/ubuntu/supertaster/node_modules/rsvp/dist/rsvp.js:2415:5)

Unfortunately, this error doesn’t help me figure out which file (or even which package) causes the syntax, so I had to do a lot of manual work to narrow it down.

The issue was introduced by https://github.com/simplabs/ember-simple-auth/commit/c295fee9b0bab6fdf7dcfca0cb706b68415caa95. So far, I haven’t been able to narrow down the syntax issue any further.