How do I solve the problem of “invalid active developer path” when attempting to use Git on VSCode

Solution 1:

xcode-select --install

This installs or updates Command Line Tools. It can be done manually too, by downloading the tools from Developer Website.

How to compile with Command Line Tools for Xcode after deleting the Xcode.app application bundle?
Can't update Developer Tools on Mojave

You might need to point it to the install location of the tools too.

sudo xcode-select -switch /Library/Developer/CommandLineTools

Then restart the Terminal/ VSCode.