Meteor publication send custom sanitized error to client in publication - meteor

Question

I am not sure if I am just doing something wrong or if this is actually not working. I want to display the original publication error on the client, in case I catched one:
Meteor.publish('somePub', function (args) {
const self = this
try {
// ... publication logic
catch (pubErr) {
self.error(pubErr)
}
})
On the client I am "catching" this error via the onStop callback:
Meteor.subscribe('somePub', args, {
onStop: function (e) {
// display e to user
}
})
However, while on the server the pubErr is a Meteor.Error and according to the documentation it should be sent to the client, the client just receives a generic sanitized error message:
on the server
{
stack: "useful stack of actual method calls",
error: "somePub.failed",
reason: "somePub.invalidArguments",
details: { arg: undefined }
}
on the client
{
stack: "long list of ddp-message calls",
isClientSafe: true,
error: 500,
reason: "Internal server error",
details: undefined,
message: "Internal server error [500]",
errorType: "Meteor.Error"
}
Note: I also tried to add the error to itself as sanitizedError field, as in the documentation mentioned, but no success either.
Am I missing something here?

Answer 1

Actually I found the answer to the issue after being pointed into the right direction.
The example code works fine on a new project, so I checked why not in my project and I found, that I did not surround the arguments validation using SimpleSchema by the try/catch (unfortunately my question was poorly designed as it missed this important fact, mainly because I abstracted away the schema validation from the publication creation):
Meteor.publish('somePub', function (args) {
pubSchema.validate(args) // throws on fail
const self = this
try {
// ... publication logic
catch (pubErr) {
self.error(pubErr)
}
})
So I thought this could not be the issue's source but here is the thing: Simple Schema is not a pure Meteor package but a NPM package and won't throw a Meteor.Error but a custom instance of Error, that actually has the same attributes (error, errorType, details) like a Meteor.Error, see this part of the source code of a validation context.
So in order to pass the correct information of a SimpleSchema validation error to the client you should
wrap it in a try/catch
add the isClientSafe flag to it
alternatively convert it to a Meteor.Error
Attach a custom Meteor.Error as sanitizedError property to it