TypeScript Error in Express Route: "No Overload Matches This Call"

Question:

I am developing an e-commerce platform using TypeScript with Express. Below is the code snippet and the error I am facing. How can I fix this issue, and why does the solution work?

Code Snippets:

User Router:

router.post('/user/:id/add-address', async (req: Request<IAddress>, res: Response) => {
  try {
    const address = await Address.create(req.body);
    const user = await User.findByIdAndUpdate(
      req.params.id,
      { $push: { address: address._id } },
      { new: true }
    );

    if (!user) {
      return res.status(404).json({
        success: false,
        message: 'User not found'
      });
    }

    return res.status(200).json({ message: 'Address added successfully', user });
  } catch (error) {
    console.error(error);
    return res.status(500).json({ message: 'Error adding address' });
  }
});

Interfaces:

1. IAddress:

import { Document } from "mongoose";

export default interface IAddress extends Document {
  name?: string;
  lastName?: string;
  email?: string;
  street: string;
  city: string;
  state: string;
  zipcode: number;
  country: string;
  phone: number;
}

2. IUser:

import mongoose from "mongoose";

export default interface IUser {
  name: string;
  email: string;
  password: string;
  phoneNumber?: string;
  address?: mongoose.Schema.Types.ObjectId[];
  wishlist?: mongoose.Schema.Types.ObjectId[];
  cart?: mongoose.Schema.Types.ObjectId[];
  orderHistory?: mongoose.Schema.Types.ObjectId[];
  paymentMethods?: mongoose.Schema.Types.ObjectId[];
  createdAt?: Date;
  updatedAt?: Date;
}

Error:

No overload matches this call.
  The last overload gave the following error.
    Argument of type '(req: Request<IAddress>, res: Response) => Promise<express.Response<any, Record<string, any>>>' is not assignable to parameter of type 'Application<Record<string, any>>'.
      Type '(req: Request<IAddress, any, any, ParsedQs, Record<string, any>>, res: Response<any, Record<string, any>>) => Promise<...>' is missing the following properties from type 'Application<Record<string, any>>': init, defaultConfiguration, engine, set, and 63 more.ts(2769)
index.d.ts(164, 5): The last overload is declared here.
(parameter) req: express.Request<IAddress, any, any, QueryString.ParsedQs, Record<string, any>>

Solution:

I got the following solution:

router.post('/user/:id/add-address', async (req: Request<IAddress>, res: Response): Promise<any> => {
  // Function logic
});

Question:

Why does adding the explicit Promise<any> type fix the issue? Could you explain the reasoning behind this solution?

Express route handlers and middlewares are expected to return nothing (void type) because the result would be discarded. The support for Promise<void> was added in Express 4 at some point to be compatible with async.

There should be no return res...:

    if (!user) {
      res.status(404).json(...);
      return;
    }

    res.status(200).json(...);
  } catch (error) {
    console.error(error);
    res.status(500).json(...);
  }