error: src refspec main does not match any error: failed to push some refs to 'https://github.com/Samantha277/Sam.git' code example

Example 1: error: src refspec master does not match any error: failed to push some refs to android studio

git commit -m "initial commit"
git push origin master

Example 2: rror: src refspec master does not match any. error: failed to push some refs to 'https://git.heroku.com/thawing-retreat-68019.git'

git push heroku HEAD:master