title: DynamoDB DocumentClient.put returns DynamoDB.putItem error unexpectedly
body: <p>I am using Dynamo DB and Node JS, and I am receiving errors with my put methods that don't make any sense.</p>
  <p>It seems almost at random that I receive an error that the DocumentClient.put is expecting the object to match the DynamoDB.putItem method, producing this error (this is one example, but I receive an error for every field):</p>
  <pre><code>InvalidParameterType: Expected params.Item['startDateTime'] to be a structure&quot;,&quot;
  </code></pre>
  <p>Here is what my Object looks like:</p>
  <pre><code>payload: {
     TableName: TABLE, 
     Item: {
      gameId: 3534422,
      awayhome: 'ATLMIN',
      startDateTime: '2020-10-18T17:00:00Z',
      location: 'Minneapolis, Minnesota',
      stadium: 'U.S. Bank Stadium',
      sport: 'nfl',
      year: 2020,
      season: 'Regular',
      awayTeam: { 
          fullName: 'Atlanta Falcons',
          shortName: 'Falcons',
          code: 'ATL' 
      },
      homeTeam: {
        fullName: 'Minnesota Vikings',
        shortName: 'Vikings',
        code: 'MIN'
      },
      gameStatus: 'Unplayed' 
  } 
  }
  </code></pre>
  <p>Here's my put call to DynamoDB from Lambda:</p>
  <pre><code>db.put(payload, function(err,data) {
      if (err) {
          console.log('update error: ', err);
          callback(err, null);
      }
      if (data) {
          console.log({ successfulUpdate: data });
      }
  })
  </code></pre>
  <p>What's strange is that it happens seemingly without any clear indication why. I'll make a small change to my Lambda function, sometimes without changing the object or DynamoDB call at all, and will receive the error.</p>