It's possible for yarn install to 'succeed' and the package files to not be present in node_modules
It's possible for yarn install to 'succeed' and the package files to not be present in node_modules but to be present in your yarn cache
It's possible for yarn install to 'succeed', the package files to not be present in node_modules but to be present in your yarn cache and the package files for dependencies of the main package to be present in node_modules
If this happens:
looking at your node_modules/.bin directory will show a broken symlink from the package name to what should be the entry script
yarn check will tell you the package is not installed (despite yarn install) having claimed to install it a few seconds ago
deleting node_modules then clearing your yarn cache and reinstalling will not fix the problem
if the package in question is Playwright, switching the project to npm will immediately fix the problem
Or ask a senior to look into it, and they'll find a line with 'test' in .yarnclean
Then wonder who thought making it possible for your package manager to delete files from node_modules after installing packages was a good idea
In hindsight, I did notice .yarnclean and even opened it. Should have looked into it more since I was scraping the bottom of the idea barrel
Loading all the data your application will ever need at the start might lead to good UX once it's loaded
But if it takes ~10 seconds to load, how many people will stick around to see that UX?
If there are merge conflicts in your lockfile, just resolve any conflicts in your pacakage.json and the next yarn/npm install will autoresolve the lockfile conflicts for you