entgql nil time field order value cause msgpack panic

[wenerme]

• The issue is present in the latest release.
• I have searched the issues of this repository and believe that this is not a duplicate.

Current Behavior 😯

v is (*time.Time)(nil), v.IsZero will panic

Expected Behavior 🤔

order works

Steps to Reproduce 🕹

https://github.com/wenerme/ent-demo/blob/fd782eec12be71f29279762951efe942378c2bd1/ent/gql_test.go#L8-L10

Your Environment 🌎

Tech	Version
Go	1.16
Ent	latest
Database	-
Driver	-

[wenerme]

relate issues vmihailenco/msgpack#306

[alexsn]

Could you add your gql schema / query that's triggering this?

[wenerme]

@alexsn order by a time field with nil value will trigger this, because *time.Time has IsZero, but the value is nil, msgpack will call the IsZero check cause panic

[alexsn]

Can you paste the graphql query that does this?

[wenerme]

query {
  data: accounts(orderBy: {field: NextContactAt,direction: ASC}) {
    edges {
      node {
        id
      }
      cursor
    }
    totalCount
  }
}

NextContactAt is a *time.Time field

[wenerme]

Here has a test to reproduce the panic for msgpack

https://github.com/vmihailenco/msgpack/blob/52b4cd1be52c96601136c77937fe3153f97fde03/msgpack_test.go#L463-L477

[alexsn]

Is NextContactAt a nillable field?

[wenerme]

@alexsn Yes

[wenerme]

This is fixed in latest msgpack