Calling EntityManager.delete with only an "ATTRIBUTE_EXISTS" expression throws an error

[GTRanger]

Actual behavior: the request throws a DynamoDBServiceException with the following message ExpressionAttributeValues must not be empty. Below is an example that reproduces the issue:

await entityManager.delete(
  MyItem,
  {
   id: "1234",
  },
  {
   where: {
     feature: "ATTRIBUTE_EXISTS"
   },
  }
)

Adding logging reveals that TypeDORM creates the following delete request:

{
  TableName: 'MyTable',
  Key: { PK: '1234' },
  ReturnConsumedCapacity: undefined,
  ConditionExpression: 'attribute_exists(#CE_feature)',
  ExpressionAttributeNames: { '#CE_feature': 'feature' },
  ExpressionAttributeValues: {} // <---- DynamoDB doesn't like this
}

Expected behavior: TypeDORM does not create an empty ExpressionAttributeValues and the request does not throw an error.