Hello,

I'm writing about an issue when performing insert/update operations using minimongo. This issue is triggered when the collection has a unique index and the insert/update will fail (could also be triggered in other circumstances that we are not aware of).

• Description: When npm-mongo version 4.0.0 was introduced, MongoError was translated into more specific error (see this PR). Since then, npm-mongo will not throw MongoError but some variation (for example MongoServerError)
• Meteor version: I am currently using Meteor 2.8.0 but reading the code of newer versions, the problem will still occur.
• Last meteor version: Before 2.8.0 we were using 1.6 and the issue was not present
• Operating system: OSX Ventura
• The expected behavior: When performing an insert/update using the minimongo, if there are unique index issues, correctly report 409 error with the index name to the client.
• The actual behavior: The client receives a 500 Error and has no way to know what happened on the server side.

How to reproduce

1. Create a meteor project with a collection that has a unique index on a field.
2. On the client side, try to insert documents using minimongo with the same value for the unique field.
3. On the client side you will receive a 500 Error.
4. On the server side the error is reported correctly: Exception while invoking method '/test/insert' MongoServerError: E11000 duplicate key error collection: meteor.test index: name_1 dup key: { name: "test" }

I think the issue comes from this catch block in the function CollectionPrototype._defineMutationMethods (allow-deny.js):

} catch (e) {
  if (
    e.name === 'MongoError' ||
    // for old versions of MongoDB (probably not necessary but it's here just in case)
    e.name === 'BulkWriteError' ||
    // for newer versions of MongoDB (https://docs.mongodb.com/drivers/node/current/whats-new/#bulkwriteerror---mongobulkwriteerror)
    e.name === 'MongoBulkWriteError' ||
    e.name === 'MinimongoError'
  ) {
    throw new Meteor.Error(409, e.toString());
  } else {
    throw e;
  }
}

Best regards,
Sebastian