Mutations having @client fields are not returning server errors to the client.

[cmnstmntmn]

Hey, i think that the well known issue like this here related to the absence of server errors, is caused by the presence of the @client directive inside the mutation response.

ServerFieldOne
ServerFieldTwo
MyClientSideResolvedField @client

Removing @client fields, is fixing the issue.

[benjamn]

@cmnstmntmn Just to make sure, you mean there's a server error for ServerFieldOne or ServerFieldTwo, but it's hidden when the MyClientSideResolvedField @client field is included in the mutation?

To implement the local field, are you using a local resolver function for that field (passing options.resolvers to the ApolloClient constructor), or a field policy read function, or something else?

[cmnstmntmn]

@benjamn no, the @client field computes two other fields. They are not included in the mutation (as input).
They're just part of the mutation response

mutation SaveTicket(
  $ID: Int
  $LocationID: Int!
  $Type: TicketType!
  $Status: TicketStatus!
  $Urgency: TicketUrgency!
  $PatientID: Int! = 0
) {
  SaveTicket(
    input: {
      ID: $ID
      LocationID: $LocationID
      Type: $Type
      Status: $Status
      Urgency: $Urgency
      PatientID: $PatientID
    }
  ) {
    ID
    Type
    Status
    Patient {
      ID
      FirstName
      LastName
      FullName @client
    }
  }
}

resolver

export const resolvers = {
  Patient: {
    FullName({FirstName, LastName}) {
      return `${FirstName} ${LastName}`;
    }
  },
}

The FullName resolver it's fine for queries; but it seems to be faulty with mutations.

As for resolvers, i'm passing them as options to the AplloClient constructor

const apolloClient = new ApolloClient({
  cache,
  connectToDevTools: false,
  typeDefs,
  resolvers,
  link,
});

[timukasr]

Having same issue. One field in mutation has @client directive. When server returns error, eg:
{"errors":[{"message":"Something went wrong, please try again"}],"data":null}
then this error is handled incorrectly by Apollo. It seems that it tries to read data.mutationField, and fails with error Cannot read property 'mutationField' of null at new ApolloError