Migrating from npm to yarn when package.json has incorrect versions

I recently started working on a pre-existing react-native project, and upon setup I encountered a lot of dependency and versioning errors. The versions on package.json are incorrect for our project, and it caused errors when I ran it until we finally decided to just copy the node_modules folder into my repository from another team member's working repo instead of using npm install.

We'd like to migrate the project to Yarn so that this doesn't continue to happen, but when I try to create a yarn.lock file using either yarn install or yarn install --check-files, I end up with wrong versions and a broken project. Is there any way to generate a yarn.lock file, and potentially a new package.json, based on the versions that are in the node_modules directory?

via StrugLife10