crash if package.json is not exist

[h13i32maru]

fs.js:565
fs.write = function(fd, buffer, offset, length, position, callback) {
                                                 ^
Error: ENOENT, no such file or directory './test/fixture/package.json'
    at Error (native)
    at Object.fs.openSync (fs.js:500:18)
    at Object.fs.readFileSync (fs.js:352:15)
    at IdentifiersDocBuilder._getInfo (/Users/h13i32maru/work/esdoc/src/Publisher/Builder/DocBuilder.js:134:21)
    at IdentifiersDocBuilder._buildLayoutDoc (/Users/h13i32maru/work/esdoc/src/Publisher/Builder/DocBuilder.js:176:21)
    at IdentifiersDocBuilder.exec (/Users/h13i32maru/work/esdoc/src/Publisher/Builder/IdentifiersDocBuilder.js:14:20)
    at publish (/Users/h13i32maru/work/esdoc/src/Publisher/publish.js:72:43)
    at /Users/h13i32maru/work/esdoc/test/src/000init.js:20:3
    at Function.generate (/Users/h13i32maru/work/esdoc/src/ESDoc.js:95:5)
    at Object.<anonymous> (/Users/h13i32maru/work/esdoc/test/src/000init.js:10:7)
    at Module._compile (module.js:460:26)
    at normalLoader (/Users/h13i32maru/work/esdoc/node_modules/babel/node_modules/babel-core/lib/babel/api/register/node.js:166:5)
    at Object.require.extensions.(anonymous function) [as .js] (/Users/h13i32maru/work/esdoc/node_modules/babel/node_modules/babel-core/lib/babel/api/register/node.js:179:7)
    at Module.load (module.js:355:32)
    at Function.Module._load (module.js:310:12)
    at Module.require (module.js:365:17)
    at require (module.js:384:17)
    at /Users/h13i32maru/work/esdoc/node_modules/mocha/lib/mocha.js:192:27
    at Array.forEach (native)
    at Mocha.loadFiles (/Users/h13i32maru/work/esdoc/node_modules/mocha/lib/mocha.js:189:14)
    at Mocha.run (/Users/h13i32maru/work/esdoc/node_modules/mocha/lib/mocha.js:422:31)
    at Object.<anonymous> (/Users/h13i32maru/work/esdoc/node_modules/mocha/bin/_mocha:398:16)
    at Module._compile (module.js:460:26)
    at Object.Module._extensions..js (module.js:478:10)
    at Module.load (module.js:355:32)
    at Function.Module._load (module.js:310:12)
    at Function.Module.runMain (module.js:501:10)
    at startup (node.js:129:16)
    at node.js:814:3
child_process.js:1389
    throw err;