Mongoose validation failed, without giving the field-name with the issue - node.js

Question

When I try to save my "Rating" schema, it gives the error
error: ValidationError: Rating validation failed
without giving the field name with the problem, neither the kind of issue (if it's about a casting, a null or missing value, or something else..)
In my schema I don't have any field "required", neither "index:true"... I just specify the types in this way:
{
ex_string_field : {type:String},
ex_number_field : {type:Number},
ex_array_field : [
{
sub_field_string : {type:String}
}
],
ex_object_field : {
sub_field_string : {type:String}
}
}
How can I find which is the field rising the error? I have many fields. Actually, without any required field, it should be pretty easy to validate an object. I guessed that if a field is not compliant, it's just ignored....
This is my system:
"mongoose": "^4.11.12",
"node" : "v8.1.3",
"npm" : "5.3.0"
And this is the full error stack track:
2017-12-5 - error: ValidationError: Rating validation failed
at ValidationError (/Volumes/HD Daniele/Sites/cashinvoice/server/node_modules/mongoose/lib/error/validation.js:28:11)
at model.Document.invalidate (/Volumes/HD Daniele/Sites/cashinvoice/server/node_modules/mongoose/lib/document.js:1658:32)
at model.Document.$set (/Volumes/HD Daniele/Sites/cashinvoice/server/node_modules/mongoose/lib/document.js:760:10)
at model._handleIndex (/Volumes/HD Daniele/Sites/cashinvoice/server/node_modules/mongoose/lib/document.js:590:14)
at model.Document.$set (/Volumes/HD Daniele/Sites/cashinvoice/server/node_modules/mongoose/lib/document.js:550:24)
at model._handleIndex (/Volumes/HD Daniele/Sites/cashinvoice/server/node_modules/mongoose/lib/document.js:574:12)
at model.Document.$set (/Volumes/HD Daniele/Sites/cashinvoice/server/node_modules/mongoose/lib/document.js:550:24)
at model.Document (/Volumes/HD Daniele/Sites/cashinvoice/server/node_modules/mongoose/lib/document.js:77:12)
at model.Model (/Volumes/HD Daniele/Sites/cashinvoice/server/node_modules/mongoose/lib/model.js:55:12)
at new model (/Volumes/HD Daniele/Sites/cashinvoice/server/node_modules/mongoose/lib/model.js:3885:13)
at /Volumes/HD Daniele/Sites/cashinvoice/server/server/routes/admin/admin-utils.js:370:13
at _fulfilled (/Volumes/HD Daniele/Sites/cashinvoice/server/node_modules/q/q.js:854:54)
at self.promiseDispatch.done (/Volumes/HD Daniele/Sites/cashinvoice/server/node_modules/q/q.js:883:30)
at Promise.promise.promiseDispatch (/Volumes/HD Daniele/Sites/cashinvoice/server/node_modules/q/q.js:816:13)
at /Volumes/HD Daniele/Sites/cashinvoice/server/node_modules/q/q.js:624:44
at runSingle (/Volumes/HD Daniele/Sites/cashinvoice/server/node_modules/q/q.js:137:13)
================== UPDATE ====================
After some testing, I ended up that the error is the complex field 'main_info'. In the specific, 2 types were swapped (a number as String, and a String as Number). They were defined as follow:
this.schema = new Schema({
main_info :
{
rea : {type:String},
name : {type:Number},
}
});
This is an example of passed data that rise the Validation Error:
main_info :
{
"rea": 649087,
"name": "NUTIS S.R.L."
}
Anyway I think that it's crazy manual parse the whole data to find which is the problem. Does Mongoose really not provide any further info about the validation fail?