회원가입시 500 에러

 {
  "name": "sansbook-back",
  "version": "1.0.0",
  "description": "",
  "main": "app.js",
  "scripts": {
    "dev": "nodemon app",
    "start": "cross-env NODE_ENV=production pm2 start app.js"
  },
  "author": "jangsan",
  "license": "ISC",
  "dependencies": {
    "bcrypt": "^5.1.0",
    "cookie-parser": "^1.4.6",
    "cors": "^2.8.5",
    "cross-env": "^7.0.3",
    "dotenv": "^16.0.3",
    "express": "^4.18.2",
    "express-session": "^1.17.3",
    "helmet": "^6.1.5",
    "hpp": "^0.2.3",
    "morgan": "^1.10.0",
    "multer": "^1.4.5-lts.1",
    "mysql2": "^3.2.0",
    "passport": "^0.6.0",
    "passport-local": "^1.0.0",
    "pm2": "^5.3.0",
    "sequelize": "^6.30.0",
    "sequelize-cli": "^6.6.0",
    "session": "^0.1.0"
  },
  "devDependencies": {
    "nodemon": "^2.0.22"
  }
}

const express = require("express");
const session = require("express-session");
const cookieParser = require("cookie-parser");
const cors = require("cors");
const app = express();
const postRouter = require("./routes/post");
const userRouter = require("./routes/user");
const postsRouter = require("./routes/posts");
const hashtagRouter = require("./routes/hashtag");
const db = require("./models");
const passportConfig = require("./passport");
const passport = require("passport");
const dotenv = require("dotenv");
const morgan = require("morgan");
const path = require("path");
const hpp = require("hpp");
const helmet = require("helmet");

dotenv.config();
db.sequelize
  .sync()
  .then(() => {
    console.log("db 연결성공");
  })
  .catch(console.error);
passportConfig();
//모드변경
if (process.env.NODE_ENV === "production") {
  app.use(morgan("combined"));
  app.use(hpp());
  app.use(helmet());
} else {
  app.use(morgan("dev"));
}

app.use(
  cors({
    origin: ["http://localhost:3000", "sansbook.com", "http://15.164.99.87"],
    credentials: true,
  })
);
app.use("/", express.static(path.join(__dirname, "uploads")));
app.use(express.json());
app.use(express.urlencoded({ extended: true }));
app.use(cookieParser(process.env.COOKIE_SECRET));
app.use(
  session({
    saveUninitialized: false,
    resave: false,
    secret: process.env.COOKIE_SECRET,
  })
);
app.use(passport.initialize());
app.use(passport.session());

app.get("/", (req, res) => {
  res.send("hello express");
});
app.use("/posts", postsRouter);
app.use("/post", postRouter);
app.use("/user", userRouter);
app.use("/hashtag", hashtagRouter);

app.listen(80, () => {
  console.log("서버실행중!");
});

회원가입 할떄 마다 500에러가 나는데 프론트 문제인가요?