composer: Composer can not find composer.json file

My composer.json:

C:\Users\jeffr\desktop\dce\dceu

{
    "name": "laravel/laravel",
    "type": "project",
    "description": "The Laravel Framework.",
    "keywords": [
        "framework",
        "laravel"
    ],
    "license": "MIT",
    "require": {
        "php": "^7.1.3",
        "doctrine/dbal": "^2.9",
        "fideloper/proxy": "^4.0",
        "google/recaptcha": "~1.1",
        "intervention/image": "^2.5",
        "laravel/framework": "5.8.*",
        "laravel/tinker": "^1.0",
        "uxweb/sweet-alert": "^2.0"
    },
    "require-dev": {
        "beyondcode/laravel-dump-server": "^1.0",
        "filp/whoops": "^2.0",
        "fzaninotto/faker": "^1.4",
        "mockery/mockery": "^1.0",
        "nunomaduro/collision": "^3.0",
        "phpunit/phpunit": "^7.5"
    },
    "config": {
        "optimize-autoloader": true,
        "preferred-install": "dist",
        "sort-packages": true
    },
    "extra": {
        "laravel": {
            "dont-discover": []
        }
    },
    "autoload": {
        "psr-4": {
            "App\\": "app/"
        },
        "classmap": [
            "database/seeds",
            "database/factories"
        ]
    },
    "autoload-dev": {
        "psr-4": {
            "Tests\\": "tests/"
        }
    },
    "minimum-stability": "dev",
    "prefer-stable": true,
    "scripts": {
        "post-autoload-dump": [
            "Illuminate\\Foundation\\ComposerScripts::postAutoloadDump",
            "@php artisan package:discover --ansi"
        ],
        "post-root-package-install": [
            "@php -r \"file_exists('.env') || copy('.env.example', '.env');\""
        ],
        "post-create-project-cmd": [
            "@php artisan key:generate --ansi"
        ]
    }
}

Output of composer diagnose:

$ composer diagnose
Checking platform settings: OK
Checking git settings:

  [ErrorException]
  proc_open(NUL): failed to open stream: No such file or directory


diagnose

When I run this command:

composer install
or composer update

I get the following output:

$ composer install
Composer could not find a composer.json file in C:\Users\jeffr\desktop\dce\dceu
To initialize a project, please create a composer.json file as described in the https://getcomposer.org/ "Getting Started" section

$ composer update
Composer could not find a composer.json file in C:\Users\jeffr\desktop\dce\dceu
To initialize a project, please create a composer.json file as described in the https://getcomposer.org/ "Getting Started" section

And I expected this to happen: it should install or update my packages