tattoo "PolymerElements/iron-input#2.0-preview"
TypeError: Cannot read property 'push' of undefined
at mergeArray (/Users/noms/.nvm/versions/node/v6.9.1/lib/node_modules/tattoo/src/cli.ts:232:20)
at Object.mergeConfigFileOptions (/Users/noms/.nvm/versions/node/v6.9.1/lib/node_modules/tattoo/src/cli.ts:249:3)
at /Users/noms/.nvm/versions/node/v6.9.1/lib/node_modules/tattoo/src/bin/tattoo.ts:24:5
at next (native)
at /Users/noms/.nvm/versions/node/v6.9.1/lib/node_modules/tattoo/lib/bin/tattoo.js:8:65
at __awaiter (/Users/noms/.nvm/versions/node/v6.9.1/lib/node_modules/tattoo/lib/bin/tattoo.js:4:12)
at main (/Users/noms/.nvm/versions/node/v6.9.1/lib/node_modules/tattoo/lib/bin/tattoo.js:14:12)
at Object.<anonymous> (/Users/noms/.nvm/versions/node/v6.9.1/lib/node_modules/tattoo/src/bin/tattoo.ts:51:1)
at Module._compile (module.js:570:32)
at Object.Module._extensions..js (module.js:579:10)