core-js?npm install && cd frontend && npm install. Notice the issue of [email protected] postinstall /opt/render/project/src/node_modules/core-js and node -e "try{require('./postinstall')}catch(e){}". I've set up my env variables on render.com, made sure my node version is the same as render, checked the root folder and build & start commands, but everything seems okay there. Here's the repo link: https://github.com/raulbarriga/MERN-FullStack-Ecommerce.