Converting circular structure to JSON\

ModuleVideoController.js

import Video from '../../models/Video';
import WatchedVideo from '../../models/WatchedVideo';

class ModuleVideoController {
  async index(req, res) {
    const { module_id, student_id } = req.params;
    
    // Busco os vídeos cadastrados no banco de dados.
    const videos = await Video.findAll({
      attributes: ['id', 'title', 'url'],
      where: [{ module_id }],
    });

    // Busco os vídeos assistidos pelo usuário "student_id".
    const watched = await WatchedVideo.findAll({
      attributes: ['video_id'],
      where: [{ module_id, student_id }],
    });
    
    // Função para incluir o watched=true ou false.
    const watched_video = videos.map((v) => {
      if (watched.some((w) => w.video_id === v.id))
        return { ...v, watched: true };
      return { ...v, watched: false };
    });
    
    // Quando efetuo o teste através do postman, recebo a mensagem no final do arquivo.
    return res.json({ watched_video }); 
  }
}

export default new ModuleVideoController();

/* ====================================================== */

//MENSAGEM DE ERRO
{
    "error": {
        "message": "Converting circular structure to JSON\n    --> starting at object with constructor 'Sequelize'\n    |     property 'dialect' -> object with constructor 'PostgresDialect'\n    --- property 'sequelize' closes the circle",
        "name": "TypeError",
        "frames": [
            {
                "file": "node_modules\\express\\lib\\response.js",
                "filePath": "C:\\MyApps\\efabet\\efabet-backend\\node_modules\\express\\lib\\response.js",
                "method": "stringify",
                "line": 1123,
                "column": 12,
                "context": {
                    "start": 1118,
                    "pre": "function stringify (value, replacer, spaces, escape) {\n  // v8 checks arguments.length for optimizing simple call\n  // https://bugs.chromium.org/p/v8/issues/detail?id=4730\n  var json = replacer || spaces\n    ? JSON.stringify(value, replacer, spaces)",
                    "line": "    : JSON.stringify(value);",
                    "post": "\n  if (escape) {\n    json = json.replace(/[<>&]/g, function (c) {\n      switch (c.charCodeAt(0)) {\n        case 0x3c:"
                },
                "isModule": true,
                "isNative": false,
                "isApp": false
            },
            {
                "file": "node_modules\\express\\lib\\response.js",
                "filePath": "C:\\MyApps\\efabet\\efabet-backend\\node_modules\\express\\lib\\response.js",
                "method": "ServerResponse.json",
                "line": 260,
                "column": 14,
                "context": {
                    "start": 255,
                    "pre": "  // settings\n  var app = this.app;\n  var escape = app.get('json escape')\n  var replacer = app.get('json replacer');\n  var spaces = app.get('json spaces');",
                    "line": "  var body = stringify(val, replacer, spaces, escape)",
                    "post": "\n  // content-type\n  if (!this.get('Content-Type')) {\n    this.set('Content-Type', 'application/json');\n  }"
                },
                "isModule": true,
                "isNative": false,
                "isApp": false
            },
            {
                "file": "src\\app\\controllers\\student_platform\\ModuleVideoController.js",
                "filePath": "C:\\MyApps\\efabet\\efabet-backend\\src\\app\\controllers\\student_platform\\ModuleVideoController.js",
                "method": "index",
                "line": 27,
                "column": 16,
                "context": {
                    "start": 22,
                    "pre": "\n    if (!watched_video.length) {\n      return res.json({ message: `Videos not found in module: ${module_id}` });\n    }\n",
                    "line": "    return res.json({ watched_video });",
                    "post": "  }\n}\n\nexport default new ModuleVideoController();\n"
                },
                "isModule": false,
                "isNative": false,
                "isApp": true
            }
        ]
    }
}