Add react-18 as peer dependency.

[alihammad-gist]

Peer dependencies do not include react-18 which causes installation errors.

❯ npm i flux --save
npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree
npm ERR!
npm ERR! While resolving: mezzio@1.0.0
npm ERR! Found: react@18.1.0
npm ERR! node_modules/react
npm ERR!   react@"^18.1.0" from the root project
npm ERR!
npm ERR! Could not resolve dependency:
npm ERR! peer react@"^15.0.2 || ^16.0.0 || ^17.0.0" from flux@4.0.3
npm ERR! node_modules/flux
npm ERR!   flux@"*" from the root project
npm ERR!
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force, or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.

[yangshun]

The Flux library is no longer being updated and we don't have intentions to make Flux compatible with React 18 as we're still using some UNSAFE_ lifecycle APIs. It's better to just migrate to another store instead if you want to upgrade to React 18.

Consider using Redux Toolkit, which is pretty good.