*Changed event with no resolver

[makoto]

The following query fails as there's a name changed event out there with no resolver set.

{
    nameChangeds(where:{blockNumber_gt:11490000}){
    id
    name
    resolver{
      domain{
        name
      }
      address
    }
  }
}

Investigate

• Whether this happens on NameChanged or all (Addr|MulticoinAddr|Abi|Pubkey|Text|Contenthash|Interface|Authorisation)Changed
• Fix the bug