Okay, great! This is a step in the right direction.
1. Good
2. Okay, so if you delete the node_modules folder and just run npm init in the plugin folder, what specific errors do you get?
3. NODE_ENV is being set automatically for you when you run npm run dev or npm run build. You should not need to set NODE_ENV manually. See these commands here? How they set that for you – https://github.com/zgordon/gutenberg-course/blob/master/jsforwp-blocks/package.json#L4-L5
Two followup questions:
4. Where are you hard coding the value of NODE_ENV?
5. When you run “npm run dev” and change something in the JS, does the file rebundle and show up properly in WordPress?