[14:28:06] Starting 'release.polyfill'...
core, buildBindingCore: /Users/justinwillis/Projects/ionic-core/dist/transpiled-angular/bindings/angular/src
core, buildCore: /Users/justinwillis/Projects/ionic-core/dist/compiled-ionic-angular/core/ionic.core.dev.js
core, buildCoreES5: /Users/justinwillis/Projects/ionic-core/dist/compiled-ionic-angular/core/ionic.core.es5.dev.js
core, buildAnimationsMinified: /Users/justinwillis/Projects/ionic-core/dist/compiled-ionic-angular/core/ionic.core.es5.dev.js
core, buildCoreES5Minified: /Users/justinwillis/Projects/ionic-core/dist/compiled-ionic-angular/core/ionic.core.es5.dev.js
core, buildCoreMinified: /Users/justinwillis/Projects/ionic-core/dist/compiled-ionic-angular/core/ionic.core.js
core, customElementPolyfillDev: /Users/justinwillis/Projects/ionic-core/dist/compiled-ionic-angular/core/ionic.core.ce.dev.js
core, shadyDomCustomElementPolyfillDev: /Users/justinwillis/Projects/ionic-core/dist/compiled-ionic-angular/core/ionic.core.sd.ce.dev.js
core, customElementPolyfillMin: /Users/justinwillis/Projects/ionic-core/dist/compiled-ionic-angular/core/ionic.core.ce.js
core, shadyDomCustomElementPolyfillMin: /Users/justinwillis/Projects/ionic-core/dist/compiled-ionic-angular/core/ionic.core.sd.ce.js
[14:28:14] 'core' errored after 12 s
[14:28:14] Error: task completion callback called too many times
    at finish (/Users/justinwillis/Projects/ionic/node_modules/orchestrator/lib/runTask.js:15:10)
    at cb (/Users/justinwillis/Projects/ionic/node_modules/orchestrator/lib/runTask.js:29:3)
    at ChildProcess.<anonymous> (/Users/justinwillis/Projects/ionic/scripts/gulp/tasks/core.ts:51:5)
    at emitTwo (events.js:106:13)
    at ChildProcess.emit (events.js:191:7)
    at maybeClose (internal/child_process.js:877:16)
    at Socket.<anonymous> (internal/child_process.js:334:11)
    at emitOne (events.js:96:13)
    at Socket.emit (events.js:188:7)
    at Pipe._handle.close [as _onclose] (net.js:498:12)
[14:28:14] 'release.prepareReleasePackage' errored after 12 s
[14:28:14] Error in plugin 'run-sequence(core)' ```

when running `gulp release.prepareReleasePackage`