title: graphql error: mutation with where not working
body: <p>I am using Prisma GraphqQL and I got this error for a mutation with where selector: 
  "You provided an invalid argument for the where selector on User"</p>
  
  <p>Mutation:</p>
  
  <pre><code>mutation UpdateUserMutation($data: UserUpdateInput!, $where: UserWhereUniqueInput!) {
    updateUser(data: $data, where: $where) {
      id
      name
      email
      role
    }
  }
  </code></pre>
  
  <p>Variables:</p>
  
  <pre><code>{
    "data": {
      "name": "alan", "email": "alan@gmail.com", "role": "ADMIN"
    },
    "where": {
      "id": "cjfsvcaaf00an08162sacx43i"
    }
  }
  </code></pre>
  
  <p>Result:</p>
  
  <pre><code>{
    "data": {
      "updateUser": null
    },
    "errors": [
      {
        "message": "You provided an invalid argument for the where selector on User.",
        "locations": [],
        "path": [
          "updateUser"
        ],
        "code": 3040,
        "requestId": "api:api:cjftyj8ov00gi0816o4vvgpm5"
      }
    ]
  }
  </code></pre>
  
  <p>Schema:</p>
  
  <pre><code>updateUser(
    data: UserUpdateInput!
    where: UserWhereUniqueInput!
  ): User
  
  
  type UserWhereUniqueInput {
    id: ID
    resetPasswordToken: String
    email: String
  }
  </code></pre>
  
  <p>Why this mutation is not working?</p>
  
  <p>With colors:
  Mutation GraphQL
  <a href="https://i.stack.imgur.com/RRzRJ.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/RRzRJ.png" alt="Mutation GraphQL"></a>
  Schema Graphql
  <a href="https://i.stack.imgur.com/uaVU1.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/uaVU1.png" alt="Schema Graphql"></a></p>
  
  <hr>
  
  <p><strong>EXTRA INFORMATION</strong></p>
  
  <p><em>Full code</em> of this Project is <a href="https://github.com/alan345/naperg" rel="nofollow noreferrer">here</a>: </p>
  
  <p><em>Graphql playground</em> is <a href="https://graphqlbin.com/Lg0Wfm" rel="nofollow noreferrer">here</a>:</p>
  
  <p><em>Console view</em> (variable are empty):
  <a href="https://i.stack.imgur.com/ujfyh.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ujfyh.png" alt="console view (variable are empty):"></a></p>
  
  <p><em>Query for user</em> (with id: cjfsvcaaf00an08162sacx43i). So user can be found with "where" operator in query, but not in mutation.
  <a href="https://i.stack.imgur.com/zsj5P.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/zsj5P.png" alt="enter image description here"></a></p>