"xcrun: error: invalid active developer path" error when trying to install Facebook fairscale to use OPT-175B

Question

I am trying to set up Metaseq's OPT-175B, and for that I need to install Fairscale from Facebook. I am unable to install Fairscale, because when I clone Fairscale's git repo, I get the error: xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun

Error:

(env) $ git clone https://github.com/facebookresearch/fairscale.git
xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun

I have tried searching for existing StackOverflow posts on the topic, but all of the similar errors occurred to other people after updates of macOS. I have not updated macOS at all since a long time. I am using macOS Monterey 12.2.1 on a 2020 Apple M1 chip.

What have I tried?

I tried copying the entire second step mentioned in the docs:

git clone https://github.com/facebookresearch/fairscale.git
cd fairscale
git checkout fixing_memory_issues_with_keeping_overlap_may24
pip3 install -e .

and recieved another error: ERROR: file:///Users/adithraghav/Documents/xyz does not appear to be a Python project: neither 'setup.py' nor 'pyproject.toml' found.

Please help me out, thanks in advance.