React app building with Yarn fails in netlify

[perry]

Hi there, give this post a read through, we think it should help:

New CI=true build configuration, "Treating warnings as errors because process.env.CI = true"

Beginning on June 15, 2020 Netlify will start a gradual rollout of adding the environment variable CI to build environments, with the value of true . This environment variable, short for Continuous Integration, is commonly set in various CI environments like Travis CI and Github Actions, among many others. The ecosystem has largely agreed to use this environment setting to detect when a build is executing in a CI environment, as opposed to a local development environment. This setting allows…