npm run build:prod fails with assetsTypeError on fresh install #473

$ npm run build:prod

> angular2-webpack-starter@4.0.0 prebuild:prod /Users/gob/tmp/angular2-webpack-starter
> npm run clean:dist


> angular2-webpack-starter@4.0.0 clean:dist /Users/gob/tmp/angular2-webpack-starter
> rimraf dist


> angular2-webpack-starter@4.0.0 build:prod /Users/gob/tmp/angular2-webpack-starter
> node --max-old-space-size=4096 ./node_modules/webpack/bin/webpack --config config/webpack.prod.js  --progress --profile --colors --display-error-details --display-cached --bail

root directory: /Users/gob/tmp/angular2-webpack-starter
14957ms build modules
21ms seal
176ms optimize
587ms hashing
121ms create chunk assets
21589ms additional chunk assets
 80% optimize chunk assetsTypeError: callback is not a function
    at Gzip.onEnd (zlib.js:227:5)
    at emitNone (events.js:72:20)
    at Gzip.emit (events.js:166:7)
    at endReadableNT (_stream_readable.js:903:12)
    at doNTCallback2 (node.js:439:9)
    at process._tickCallback (node.js:353:17)

npm ERR! Darwin 15.0.0
npm ERR! argv "/usr/local/bin/node" "/usr/local/bin/npm" "run" "build:prod"
npm ERR! node v4.2.1
npm ERR! npm  v2.10.0
npm ERR! code ELIFECYCLE
npm ERR! angular2-webpack-starter@4.0.0 build:prod: `node --max-old-space-size=4096 ./node_modules/webpack/bin/webpack --config config/webpack.prod.js  --progress --profile --colors --display-error-details --display-cached --bail`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the angular2-webpack-starter@4.0.0 build:prod script 'node --max-old-space-size=4096 ./node_modules/webpack/bin/webpack --config config/webpack.prod.js  --progress --profile --colors --display-error-details --display-cached --bail'.
npm ERR! This is most likely a problem with the angular2-webpack-starter package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR!     node --max-old-space-size=4096 ./node_modules/webpack/bin/webpack --config config/webpack.prod.js  --progress --profile --colors --display-error-details --display-cached --bail
npm ERR! You can get their info via:
npm ERR!     npm owner ls angular2-webpack-starter
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR!     /Users/gob/tmp/angular2-webpack-starter/npm-debug.log

0 info it worked if it ends with ok
1 verbose cli [ '/usr/local/bin/node',
1 verbose cli   '/usr/local/bin/npm',
1 verbose cli   'run',
1 verbose cli   'build:prod' ]
2 info using npm@2.10.0
3 info using node@v4.2.1
4 verbose run-script [ 'prebuild:prod', 'build:prod', 'postbuild:prod' ]
5 info prebuild:prod angular2-webpack-starter@4.0.0
6 verbose unsafe-perm in lifecycle true
7 info build:prod angular2-webpack-starter@4.0.0
8 verbose unsafe-perm in lifecycle true
9 info angular2-webpack-starter@4.0.0 Failed to exec build:prod script
10 verbose stack Error: angular2-webpack-starter@4.0.0 build:prod: `node --max-old-space-size=4096 ./node_modules/webpack/bin/webpack --config config/webpack.prod.js  --progress --profile --colors --display-error-details --display-cached --bail`
10 verbose stack Exit status 1
10 verbose stack     at EventEmitter.<anonymous> (/usr/local/lib/node_modules/npm/lib/utils/lifecycle.js:213:16)
10 verbose stack     at emitTwo (events.js:87:13)
10 verbose stack     at EventEmitter.emit (events.js:172:7)
10 verbose stack     at ChildProcess.<anonymous> (/usr/local/lib/node_modules/npm/lib/utils/spawn.js:24:14)
10 verbose stack     at emitTwo (events.js:87:13)
10 verbose stack     at ChildProcess.emit (events.js:172:7)
10 verbose stack     at maybeClose (internal/child_process.js:818:16)
10 verbose stack     at Process.ChildProcess._handle.onexit (internal/child_process.js:211:5)
11 verbose pkgid angular2-webpack-starter@4.0.0
12 verbose cwd /Users/gob/tmp/angular2-webpack-starter
[...]
20 verbose exit [ 1, true ]