I'm trying to create an Auth service for my application. I have thrown the error from the .then().catch(), but it wasn’t caught by the try-catch.

async logIn(
        req: Request,
        res: Response,
        next: NextFunction
    ): Promise>> {
        try {
            const { userName, password } = req.body;
            const user = await this.userService.getUserByPassword(
                userName,
                password
            );

            if (user) {
                const userData: UserData = {
                    id: user.id,
                    email: user.email,
                    firstName: user.firstName,
                    lastName: user.lastName,
                    userName: user.userName
                };

                this.authService
                    .generateAccessToken(userData, ROLE.admin)
                    .then((accessToken) => {
                        return res.cookie('token', accessToken).json(userData);
                    })
                    .catch((err) => {
                        // thrown from here
                        throw err;
                    });
            }
        } catch (err) {
            const error = errorHandler(err);

            return res.status(400).send(error);
        }
    }

Why did this happen ?