The server build uses a specific version of yarn and node. We should try to get tooling in place to help ensure developers are using the same yarn version as the build. We have nvm available for setting the node version, but nothing yet for yarn.
The maven-frontend-plugin does use a specific version of yarn (from the system property yarn.version). If we find a pure-JS tool for managing this, we should ensure that it and maven-frontend-plugin get the version number from the same place (eg parsing the same properties file or something).