git-mikado/src/commands/new_branch.ts

import Git from 'simple-git';

async function check_workspace_clean() {
   return Git().status().then( (result) => {
       if(!result.isClean()) throw new Error('workspace not clean, aborting');
   })
}

export default async () => {
    await check_workspace_clean();

    console.log( 'yay');
}