Use "response_action" to respond to view_submission when using botkit

I have a simple modal with view pushed using:

           const result = await bot.api.views.open({
                trigger_id: message.trigger_id,
                view: {
                    "type": "modal",
                    "submit": {
                        "type": "plain_text",
                        "text": "Submit",
                        "emoji": true
                    },
                    "title": {
                        "type": "plain_text",
                        "text": "Request",
                        "emoji": true
                    },
                    "blocks": [
                        {
                            "type": "input",
                            "block_id" : "accblock",
                            "element": {
                                "type": "plain_text_input",
                                "action_id": "account_name",
                                "multiline": false
                            },
                            "label": {
                                "type": "plain_text",
                                "text": "Account Name",
                                "emoji": true
                            }
                        }
                    ]
                }
            });

I need to add error to the block if certain value is entered on view_submission. I understand I should send response with the following JSON:

       {
          response_action: 'errors',
          errors: {
            "ticket-desc": 'I will never accept a value, you are doomed!'
          }
        }

But, how do I send it? I've tried using bot.httpBody(). Does this JSON need to be included as the view object? Any help is appreciated.

bot.httpBody() is the method you need.

Make sure that the key to the errors dictionary matches the block_id of the element you are providing an error message for.

In your case this will work:

bot.httpBody({
  response_action: 'errors',
  errors: {
    accblock: 'Your account name is invalid or in use.'
  }
})

You do not need to JSON.stringify the response message and indeed the process fails if you do.