Middleware `next()` function preventing `handleError()` from being called in resource routes

[rossipedia]

Reproduction

(🇺🇸🎆 Happy 4th! 🎆🇺🇸)

Go to https://stackblitz.com/~/github.com/rossipedia/rr-middleware-handle-error-shenanigans

Make a request to /, you should see *** HANDLE ERROR *** in the terminal output.

Make a request to /?next=true. You should NOT see the handle error output.

The only difference between those two scenarios is that one calls next() in a middleware, and one does not.

Note

This only seems to affect Resource Routes. Exporting a default component from _index.tsx causes handleError() to be invoked as expected in both cases.

• Update •

Looks like this only happens with Resource Route document requests; ie: they do not have the .data suffix.

I've updated the repo to rename _index.tsx to test.tsx (because I couldn't remember how to trigger a data request for _index 😅).

# DOES NOT produce the `handleError` output
❯ curl 'localhost:5173/test?next=true'
Error: Foo

# DOES produce the `handleError` output
❯ curl 'localhost:5173/test.data?next=true'
[{"_1":2},"routes/test",{"_3":4},"error",["SanitizedError",5,6,7],"Error","Foo","Error: Foo\n    at loader ...

System Info

System:
    OS: macOS 15.5
    CPU: (16) arm64 Apple M4 Max
    Memory: 2.43 GB / 64.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.16.0 - ~/.local/state/fnm_multishells/3459_1751671592366/bin/node
    Yarn: 1.22.22 - ~/.local/state/fnm_multishells/3459_1751671592366/bin/yarn
    npm: 11.4.2 - ~/src/rr/rr-middleware-handle-error-shenanigans/node_modules/.bin/npm
    pnpm: 10.12.1 - ~/.local/state/fnm_multishells/3459_1751671592366/bin/pnpm
    bun: 1.2.18 - /opt/homebrew/bin/bun
  Browsers:
    Chrome: 137.0.7151.120
    Safari: 18.5
  npmPackages:
    @react-router/dev: ^7.6.1 => 7.6.3 
    @react-router/fs-routes: ^7.6.1 => 7.6.3 
    @react-router/node: ^7.6.1 => 7.6.3 
    @react-router/serve: ^7.6.1 => 7.6.3 
    react-router: ^7.6.1 => 7.6.3 
    vite: ^6.3.5 => 6.3.5

Used Package Manager

npm

Expected Behavior

I expect the same behavior in both cases:

handleError should be invoked when an error is thrown, regardless of whether or not there is a middleware that calls next() or not.

Actual Behavior

If the middleware calls next(), then the error is never propagated to handleError.