Попробуйте заменить .data
на .send
На основании комментариев в источнике:
/**
* Send `data`, defaulting the `.type()` to "json" when
* an object is given.
*
* Examples:
*
* // querystring
* request.get('/search')
* .send({ search: 'query' })
* .end(callback)
*
* // multiple data "writes"
* request.get('/search')
* .send({ search: 'query' })
* .send({ range: '1..5' })
* .send({ order: 'desc' })
* .end(callback)
*
* // manual json
* request.post('/user')
* .type('json')
* .send('{"name":"tj"})
* .end(callback)
*
* // auto json
* request.post('/user')
* .send({ name: 'tj' })
* .end(callback)
*
* // manual x-www-form-urlencoded
* request.post('/user')
* .type('form')
* .send('name=tj')
* .end(callback)
*
* // auto x-www-form-urlencoded
* request.post('/user')
* .type('form')
* .send({ name: 'tj' })
* .end(callback)
*
* @param {String|Object} data
* @return {Request} for chaining
* @api public
*/