to see the error

1. cd into this directory
2. cd RNapp && npm install --no-optional && cd .. (otherwise you will get an error that @scope/ui could not be found. if you want to use yarn, make sure to remove @scope/ui module from the package.json before running yarn, you can add it back after the command has finished)
3. mkdir RNapp/node_modules/@scope && cd RNapp/node_modules/@scope && ln -s ../../../ scoped-module ui && cd ../../
4. yarn start
5. run XCode and try the app

to fix the error

1. shut down the running instance of metro
2. cd into this directory
3. mv RNapp/node_modules/@scope/ui RNapp/node_modules/@scope/linked-ui
4. cp -r scoped-module RNapp/node_modules/@scope/u i
5. cd RNapp && yarn start --reset-cache
6. run XCode and try the app