javascript - Uncaught exception onReject callback Promise -

since yesterday , try understand behavior did not know onreject promise callback. in fact, work api (return json data) , superagent make request. have class:

class api {     constructor(uri) {         ...     }      // simple http request     get(...) {         var url = this.buildurl(...);         this.requestpending = request.get(url);         return new promise((resolve, reject) => {             this.requestpending.end((err, res) => {                 if (err) {                     reject(res.body.error);                 } else {                     resolve(res.body);                 }             });         });     } } 

what not understand that:

reject(res.body.error); 

throw exception (res.body.error contains simple string). indeed, firebug display error:

uncaught exception: ... 

could explain behavior ?

ps: work babel transpile js.

edit

i tested when librairie have same result. however, when write:

reject(new error("foo")); 

the onreject callback never call:

when.all([    api.get(...),    api.get(...) ]).then(data => {    console.log(data) }, err => {    console.log(err); }) 

and in browser:

i continue research.

edit 2

really sorry , deserve whipped on public square !!!. in fact, had change 1 file instead of two. really, sorry !!

i dont know whether silly or not,may scope requestpending might problem.sorry if sounds silly,

 var url = this.buildurl(...),self = this;         this.requestpending = request.get(url);         return new promise((resolve, reject) => {             self.requestpending.end((err, res) => {                 if (err) {                     reject(res.body.error);                 } else {                      resolve(res.body);                 }             });         });     } }