OK to fix this run these commands in order:
// This will delete node_modules folder rm -rf node_modules
// this will delete package-lock.json file. rm package-lock.json
// This will clear the cache. npm cache clear --force
Now re-Install everything along with Cross-env
// This will install cross env. npm install cross-env
// this will install rest of the packages based of your package.json file. npm install
Now all should work try using below command
npm run dev
Cheers