debug extension always building

[tjx666]

I use the typescript to configure webpack to bundle my extension, so I set the npm scripts as follow:

"scripts": {
        "vscode:prepublish": "yarn run build",
        "compile": "cross-env NODE_ENV=development ts-node --files ./scripts/pack.ts ",
        "build": "cross-env NODE_ENV=production ts-node --files ./scripts/pack.ts",
        "watch": "cross-env NODE_ENV=development ts-node --files ./scripts/pack.ts --watch",
        "pretest": "yarn run compile",
        "test": "node ./out/test/runTest.js",
        "lint": "lint-staged"
    }

But after I clicked the bebug button, VSCode is alway building:

How can I debug the extension in this way?

version info:

Version: 1.40.2 (user setup)
Commit: f359dd69833dd8800b54d458f6d37ab7c78df520
Date: 2019-11-25T14:54:45.096Z
Electron: 6.1.5
Chrome: 76.0.3809.146
Node.js: 12.4.0
V8: 7.6.303.31-electron.0
OS: Windows_NT x64 10.0.18363