I have this strange issue with DynamoDB where I cannot seem to update an item.

Here is my command:

TableName: 'UserTable',
Key: { UID: { S: 'h4XJj3YRxZiF7TDcGkxAhc' } },
UpdateExpression: 'SET numRatings = :numRatings',
ExpressionAttributeValues: { ':numRatings': { N: 336 } },
ReturnValues: 'UPDATED_NEW'

I have verified that the table is correct, and that the key of the table UID does indeed have the hash h4XJj3YRxZiF7TDcGkxAhc as a value. numRatings currently is equal to 1.

Here's my code:

  const params = {
    TableName: process.env.USER_TABLE_NAME!,
    Key: {
      UID: {
        S: UID
      }
    },
    UpdateExpression: 'SET numRatings = :numRatings',
    ExpressionAttributeValues: {
      ':numRatings': { N: numRatings } as unknown as AttributeValue
    },
    ReturnValues: 'UPDATED_NEW'
  } as UpdateItemCommandInput;

  try {
    const result = await dbClient.send(new UpdateItemCommand(params));
...

Yet I get this error: NUMBER_VALUE cannot be converted to String maybe I am blind but I cannot see where this conversion could be taking place.

I am using TypeScript and AWS-SDK 3.54.0

If anyone is able to point out what I am doing wrong I would greatly appreciate it.