error: npm run serve

[luics]

> weex@0.4.0 build:copy2sdk /Users/luics/Documents/proj/sandbox/weex
> cp -vf ./src/js-framework/dist/index.js ./android/sdk/assets/main.js

cp: ./android/sdk/assets/main.js: No such file or directory

npm ERR! Darwin 15.0.0
npm ERR! argv "/usr/local/bin/node" "/usr/local/bin/npm" "run" "build:copy2sdk"
npm ERR! node v4.2.6
npm ERR! npm  v2.14.12
npm ERR! code ELIFECYCLE
npm ERR! weex@0.4.0 build:copy2sdk: `cp -vf ./src/js-framework/dist/index.js ./android/sdk/assets/main.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the weex@0.4.0 build:copy2sdk script 'cp -vf ./src/js-framework/dist/index.js ./android/sdk/assets/main.js'.
npm ERR! This is most likely a problem with the weex package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR!     cp -vf ./src/js-framework/dist/index.js ./android/sdk/assets/main.js
npm ERR! You can get their info via:
npm ERR!     npm owner ls weex
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR!     /Users/luics/Documents/proj/sandbox/weex/npm-debug.log

npm ERR! Darwin 15.0.0
npm ERR! argv "/usr/local/bin/node" "/usr/local/bin/npm" "run" "build"
npm ERR! node v4.2.6
npm ERR! npm  v2.14.12
npm ERR! code ELIFECYCLE
npm ERR! weex@0.4.0 build: `npm run build:js-framework && npm run build:h5-render && npm run build:copy2sdk`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the weex@0.4.0 build script 'npm run build:js-framework && npm run build:h5-render && npm run build:copy2sdk'.
npm ERR! This is most likely a problem with the weex package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR!     npm run build:js-framework && npm run build:h5-render && npm run build:copy2sdk
npm ERR! You can get their info via:
npm ERR!     npm owner ls weex
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR!     /Users/luics/Documents/proj/sandbox/weex/npm-debug.log

npm ERR! Darwin 15.0.0
npm ERR! argv "/usr/local/bin/node" "/usr/local/bin/npm" "run" "serve"
npm ERR! node v4.2.6
npm ERR! npm  v2.14.12
npm ERR! code ELIFECYCLE
npm ERR! weex@0.4.0 serve: `npm run dev && npm run build && serve ./ -p 12580`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the weex@0.4.0 serve script 'npm run dev && npm run build && serve ./ -p 12580'.
npm ERR! This is most likely a problem with the weex package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR!     npm run dev && npm run build && serve ./ -p 12580
npm ERR! You can get their info via:
npm ERR!     npm owner ls weex
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR!     /Users/luics/Documents/proj/sandbox/weex/npm-debug.log

[luics]

add .gitkeeper in android/sdk/assets.