error log on npm start - node.js

Question

I know there is a lot of questions about that but I can't resolve it by myself, because I'm not sure about what the error log talks about.
Here it is:
0 info it worked if it ends with ok
1 verbose cli [ 'C:\\Program Files\\nodejs\\\\node.exe',
1 verbose cli 'C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js',
1 verbose cli 'start' ]
2 info using npm#2.5.1
3 info using node#v0.12.1
4 verbose node symlink C:\Program Files\nodejs\\node.exe
5 verbose run-script [ 'prestart', 'start', 'poststart' ]
6 info prestart essai_mongo#0.0.0
7 info start essai_mongo#0.0.0
8 verbose unsafe-perm in lifecycle true
9 info essai_mongo#0.0.0 Failed to exec start script
10 verbose stack Error: essai_mongo#0.0.0 start: `node ./bin/www`
10 verbose stack Exit status 1
10 verbose stack at EventEmitter.<anonymous> (C:\Program Files\nodejs\node_modules\npm\lib\utils\lifecycle.js:213:16)
10 verbose stack at EventEmitter.emit (events.js:110:17)
10 verbose stack at ChildProcess.<anonymous> (C:\Program Files\nodejs\node_modules\npm\lib\utils\spawn.js:14:12)
10 verbose stack at ChildProcess.emit (events.js:110:17)
10 verbose stack at maybeClose (child_process.js:1008:16)
10 verbose stack at Process.ChildProcess._handle.onexit (child_process.js:1080:5)
11 verbose pkgid essai_mongo#0.0.0
12 verbose cwd C:\Users\***\essai_mongo
13 error Windows_NT 6.1.7601
14 error argv "C:\\Program Files\\nodejs\\\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js" "start"
15 error node v0.12.1
16 error npm v2.5.1
17 error code ELIFECYCLE
18 error essai_mongo#0.0.0 start: `node ./bin/www`
18 error Exit status 1
19 error Failed at the essai_mongo#0.0.0 start script 'node ./bin/www'.
19 error This is most likely a problem with the essai_mongo package,
19 error not with npm itself.
19 error Tell the author that this fails on your system:
19 error node ./bin/www
19 error You can get their info via:
19 error npm owner ls essai_mongo
19 error There is likely additional logging output above.
20 verbose exit [ 1, true ]
Also, here is my package.json
{
"name": "essai_mongo",
"version": "0.0.0",
"private": true,
"scripts": {
"start": "node ./bin/www"
},
"dependencies": {
"body-parser": "~1.12.0",
"cookie-parser": "~1.3.4",
"debug": "~2.1.1",
"express": "~4.12.2",
"jade": "~1.9.2",
"morgan": "~1.5.1",
"serve-favicon": "~2.2.0",
"mongoose": "^4.0.0"
}
}
I don't know if i't about administratot rights, start path on package.json (I've tried C:\Users\***\essai_mongo\bin\www), environment variable,.. Any help would be appreciate