Fixed: res.format crashing when only default option is provided

[behcet]

res.format crashes when provided only the default parameter.

Code:

 res.format({
'default': function () {
res.status(statusCode).send({ error: error });
}
});

Stack:

TypeError: Object application/json has no method 'replace'
at Mime.lookup (/expressApp/node_modules/express/node_modules/send/node_modules/mime/mime.js:70:18)
at exports.normalizeType (/expressApp/node_modules/express/lib/utils.js:103:21)
at ServerResponse.res.format (/expressApp/node_modules/express/lib/response.js:613:30)
at /expressApp/index.js:61:7

curl request
curl -H 'Content-Type: application/json' -H 'Accept: application/json' -v htt p://127.0.0.1:5555/

After brief debugging response.js > res.format function I found that req.accepts() short circuits when !keys.length (which is zero, since we deleted obj.default) and returns internal function this.negotiator.mediaTypes(), which is in array type. Then it calls mime.lookup(type) on utils.js > exports.normalizeType with the array which we previously got from req.accepts, and crashes.

[dougwilson]

Great find!

[dougwilson]

Just skip calling req.accepts when keys.length === 0