Cannot inject null value dependency - "TypeInfo not known for undefined"

[Able1991]

Summary

TSyringe throws a runtime error when trying to inject dependencies with null values, even when properly registered in the container.

Environment

• TSyringe version: 4.8.0
• TypeScript version: 5.5.2
• Node.js version: 20.x

Minimal Reproduction

import "reflect-metadata";
import { container, injectable, inject } from "tsyringe";

interface User {
  id: string;
  email: string;
}

@injectable()
class UserService {
  constructor(@inject("currentUser") private currentUser: User | null) {}
}

// Register dependency with null value
container.register("currentUser", { useValue: null });

// This throws an error!
const userService = container.resolve(UserService);

Error:

Cannot inject the dependency "currentUser" at position #0 of "UserService" constructor. Reason:
    TypeInfo not known for "undefined"

Expected Behavior

The code should work without errors and inject null as the value for currentUser.

Actual Behavior

TSyringe throws a runtime error because it tries to treat the null value as a class constructor.

Additional Notes

• The error persists even when using @inject("currentUser", { isOptional: true })
• This is a common pattern in web applications for optional user authentication
• The error occurs in dependency-container.js when accessing ctor.name on a null value

Use Cases

This pattern is needed for:

• GraphQL resolvers with optional authentication
• Express middleware for both authenticated and anonymous users
• Per-request dependency injection where user context might be null
• Services with different behavior for logged-in vs anonymous users

https://github.com/Able1991/tsyringe-issue