Meteor publication send custom sanitized error to client in publication

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