title: Prisma Query resolver fails: "invalid argument for the where selector"
body: <p>I set up <code>prisma</code> with a <code>graphql yoga</code> server and have both GraphQL playgrounds available.</p>
  
  <p>I could successfully create a conversation that I'm now trying to retrieve. I can't get this simple resolver to work in the Yoga GraphQL Playground:</p>
  
  <pre><code>const resolvers = {
      Query: {
          conversation(parent: any, { id }: { id: string }, { prisma }: Context) {
              return prisma.conversation( { id } )
          }
      },
      Mutation: mutation
  }
  </code></pre>
  
  <p>I used this query:</p>
  
  <pre><code>query getConversation {
    conversation(where: {
      id: "cjrqzinj4004e0a30ch4pccml"
    }) {
      id
      title    
    }
  }
  </code></pre>
  
  <p>Error message is:</p>
  
  <pre><code>{
    "data": {
      "conversation": null
    },
    "errors": [
      {
        "message": "You provided an invalid argument for the where selector on Conversation.",
        "locations": [
          {
            "line": 2,
            "column": 3
          }
        ],
        "path": [
          "conversation"
        ],
        "code": 3040,
        "requestId": "local:cjrsahjoo00ai0a30a5y8mnvp"
      }
    ],
    "extensions": {}
  }
  </code></pre>
  
  <p>The query works in the Prisma GraphQL playground.</p>
  
  <p>Here is my data model:</p>
  
  <pre><code>type User {
    id: ID! @unique
    oauthId: String! @unique
    display: String!
    picture: String!
    likes: [Comment!]! @relation(name: "Likes")
    dislikes: [Comment!]! @relation(name: "Dislikes")
    bookmarks: [Comment!]! @relation(name: "Bookmarks")
    authorOf: [Comment!]! @relation(name: "Author")
    starterOf: [Conversation!]! @relation(name: "Starter")
  }
  
  type Attachment {
      id: ID! @unique
      name: String!
      createOn: DateTime!
      mediaType: String!
      comment: Comment! @relation(name: "Attachments")
  }
  
  type Comment {
      id: ID! @unique
      author: User! @relation(name: "Author")
      content: String!
      createDate: DateTime!
      parentConversation: Conversation @relation(name: "Conversation")
      parentComment: Comment @relation(name: "Replies")
      comments: [Comment!]! @relation(name: "Replies")
      bookmarkedBy: [User!]! @relation(name: "Bookmarks")
      likedBy: [User!]! @relation(name: "Likes")
      dislikedBy: [User!]! @relation(name: "Dislikes")
      attachments: [Attachment!]! @relation(name: "Attachments")
  }
  
  enum ParentType {
      Organization,
      Portfolio,
      Project,
      WbsComponent,
      WorkItem
  }
  
  type Parent {
      id: ID! @unique
      parent: String! @unique
      type: ParentType!
      conversations: [Conversation!]! @relation(name: "Parent")
  }
  
  type Conversation {
      id: ID! @unique
      parent: Parent! @relation(name: "Parent")
      organization: String!
      title: String!
      author: User! @relation(name: "Starter")
      createdOn: DateTime!
      comments: [Comment!]! @relation(name: "Conversation")
  }
  </code></pre>