Errors while creating full-stack web application with Python - flask, NPM, Webpack and React

Important NOTE: 

Q: Do I've to use virtul environment to run flask-react app?

Solution : No you don't have to. You can use pipenv if you want.

virtualenv is like creating a world in which you install all the dependencies you need for your app. This is great because virtualenv avoids the need to install Python packages globally. When a virtualenv is active, pip will install packages within the environment, which does not affect the base Python installation in any way.

1.  

 65% building modules 460/461 modules 1 active ...fullstack\static\css\fullstack.css(node:18056) DeprecationWarning: Chunk.modules is deprecated. Use Chunk.getNumberOfModules/mapModules/forEachModule/containsModule instead.

(Use `node --trace-deprecation ...` to show where the warning was created)

Hash: 393431d1931506f5755a

Version: webpack 3.12.0   

Time: 6025ms

====> latest version is webpack 5.24

update webpack:  npm install webpack@latest

ref: NPM Error - Missing Script : Watch · Issue #313 · JeremyEnglert/JointsWP · GitHub

2. npm run watch not working 

3. NPM Error - Missing Script : Watch