clientLoader hydration message shows in SPA that doesn't use clientLoader

[joryphillips]

Reproduction

1. Fork https://github.com/joryphillips/macarons, a Remix SPA project using React 19.0.0-rc-a960b92c-20240819 so that HMR works, that does not include any clientLoader functions
2. Use npm run dev to see console message mentioned below
3. Use npm run build and then serve it to also see console message in hosted build

The message is

💿 Hey developer 👋. You can provide a way better UX than this when your app is running `clientLoader` functions on hydration. Check out https://remix.run/route/hydrate-fallback for more information.

System Info

System:
    OS: macOS 14.6.1
    CPU: (14) arm64 Apple M3 Max
    Memory: 1.24 GB / 36.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 20.11.1 - ~/.nvm/versions/node/v20.11.1/bin/node
    npm: 10.8.2 - ~/.nvm/versions/node/v20.11.1/bin/npm
  Browsers:
    Safari: 17.6
  npmPackages:
    @remix-run/css-bundle: 2.11.2 => 2.11.2 
    @remix-run/dev: 2.11.2 => 2.11.2 
    @remix-run/eslint-config: 2.11.2 => 2.11.2 
    @remix-run/node: 2.11.2 => 2.11.2 
    @remix-run/react: 2.11.2 => 2.11.2 
    @remix-run/serve: 2.11.2 => 2.11.2 
    vite: ^5.4.1 => 5.4.1

Used Package Manager

npm

Expected Behavior

SPA project with no clientLoader functions should not have console message about clientLoaders, especially in the final build

Actual Behavior

SPA project with no clientLoader functions is showing console message about clientLoaders in both dev and build

[brophdawg11]

This message should probably be tweaked so it's not specific to clientLoader but the message is accurate. In SPA mode even without client loaders - your application has to load all of the JS bundles before it can render anything to the user. Without a HydrateFallback you just show the user a completely blank white screen while all of that is loading. Remix encourages you to add a root HydrateFallback to show them some sort of loading message or spinner or something. That HydrateFallback ends up in the initial index.html document so it shows to the user immediately.

[joryphillips]

I was wondering if that might be the case.

I did try adding a HydrateFallback but for some reason my app got stuck on that and never hydrated. I'll take another look at that.