First, make sure that you have installed Visual Studio Code , node.js 8.X and npm 5.X version. You can check it on your terminal window by merely entering node -v and npm -v. You can also download latest nodeJs from here
$ npm -v$ node -v
once node and npm install on your machine, we need to install Ionic globally as well.
// You can install ionic globally on your machine with below command$ npm install -g ionic$ npm install -g cordova
Ionic is recently doing lots of changes with ionic V4 and default if it installs ionic-cli V4 which might break few things if you still running our ionic V3. Most probably their app-script module needs to update with the latest one then this app run correctly with ionic cli V4 as well.
Make sure you have installed ionic-cli latest release and Cordova. You can check ionic version in the terminal with ionic -v command. If you need more info how to setup ionic project please follow Ionic Getting Started at Ionic official websites.
You need XCODE AND Android Studio to make production build that can upload on app store.
We suggest to use ionic pro to make native build easier as setup through Xcode and android studio bit difficult if you new on app development.
You might receive some other git related Error or node-sass as well .
If you get this error, please check if git was installed on your machine and if you are window user git should be in your path of the device
If there any error related to node-saas you may follow the guide based on your machine OS and most of the case window user might face issue then you can install Python 2.X on your machine, and it probably resolves your Error.