Type resolution for express ~ 4.21.2 is wrong, pulls @types/express v5 instead of v4

[m-a-rahal-os]

Issue

I recently done an upgrade of my packages, namely:

• from express-session@1.18.0 to express-session@1.18.1
• from express@4.19.2 to express@4.21.2

And I noticed that there are some typing issues (I'm not alone, see this issue in express).

Solution / TL;DR

As stated in this answer the problem is that express-session is wrongly pulling @types/express@5 instead of ^4.17.5, when running yarn why @types/express I get:

yarn why @types/express                    07:39:00
yarn why v1.22.22
[1/4] Why do we have the module "@types/express"...?
[2/4] Initialising dependency graph...
[3/4] Finding dependency...
[4/4] Calculating file sizes...
=> Found "@types/express@4.17.21"
info Has been hoisted to "@types/express"
info This module exists because it's specified in "devDependencies".
info Disk size without dependencies: "20KB"
info Disk size with unique dependencies: "128KB"
info Disk size with transitive dependencies: "2.76MB"
info Number of shared dependencies: 7
=> Found "@types/express-session#@types/express@5.0.0"
info This module exists because "@types#express-session" depends on it.
info Disk size without dependencies: "20KB"
info Disk size with unique dependencies: "128KB"
info Disk size with transitive dependencies: "2.76MB"
info Number of shared dependencies: 7
Done in 0.28s.

The solution was to (again, thanks to this answer) to force "resolutions" (or "overrides" for nmp) in package.json as follows:

"resolutions": {
   "**/@types/express": "^4.17.21"
 }

How to reproduce

Create a project with the following dependencies (package.json):

{
  "dependencies": { 
    "express": "^4.19.2",
    "express-session": "^1.18.0",
  },
  "devDependencies": {
    "@types/express": "^4.17.21",
    "@types/express-session": "^1.18.0",
    "typescript": "^5.4.3"
}

And this code

// index.ts
import session from "express-session";
import express from "express";

const app = express();

app.use(
  session({ /* session details */ })   // <--- error on this line
);

I get the following error No overload matches this call. Argument of type 'RequestHandler<ParamsDictionary, any, any, ParsedQs, Record<string, any>>' is not assignable to parameter of type 'PathParams'.ts(2769)

Thanks for your time.

[alexleboucher]

+1

[rajephon]

+1