Misleading error message when filtering with `_id: { $exists: <boolean> }` in collections

[toptobes]

Example (the same holds when using $exists: false or having other fields in the filter as well):

command: {
  deleteMany: { filter: { _id: { '$exists': true } } }
},
rawResponse: {
  errors: [
    {
      message: 'Invalid filter expression: $exists operator must have `BOOLEAN`',
      errorCode: 'INVALID_FILTER_EXPRESSION',
      id: '7a94d466-e9eb-4cef-8153-0454c65522d6',
      family: 'REQUEST',
      title: 'Invalid filter expression',
      scope: 'FILTER'
    }
  ]
}

Using $exists on other fields doesn't seem to cause issues (e.g. { other_field: { $exists: true } }).

I haven't extensively tested, but I believe the issue is universal with any filter, not just on deleteMany. Here's findOne, for example, having the same issue:

command: {
  findOne: {
    filter: { _id: { '$exists': false } }
  }
},
rawResponse: {
  errors: [
    {
      message: 'Invalid filter expression: $exists operator must have `BOOLEAN`',
      errorCode: 'INVALID_FILTER_EXPRESSION',
      id: '4893310d-ed09-4af0-8463-edd71e034c2e',
      family: 'REQUEST',
      title: 'Invalid filter expression',
      scope: 'FILTER'
    }
  ]
}