when `trailingSlash: always` loaders do not run if the trailing-slash is not present

[SeanCassiere]

Describe the bug

From @TkDodo

found a small issue with route loaders and trailingSlash: always:

the loaders don't run if I navigate to a route without a trailing slash, like /about. This can happen if the user types in the url manually. What happens is:

• the router appends a slash /about/
• it renders the right component
• but the loader of that component never runs.

reproduction: https://stackblitz.com/edit/tanstack-router-lhw7fj?file=src%2Fmain.tsx,src%2Froutes%2F__root.tsx,src%2Froutes%2Fabout.tsx&preset=node

if you navigate with the link to About, it will work, but if you open the sandbox preview in a new tab and go to /about, it doesn't work (I hope this link works): https://tanstackrouterlhw7fj-yhec--3001--9e2d28a3.local-credentialless.webcontainer.io/about (mising trailing slash on purpose)

it works fine with trailingSlash: 'preserve'

Your Example Website or App

https://stackblitz.com/edit/tanstack-router-lhw7fj?file=src/main.tsx,src/routes/__root.tsx,src/routes/about.tsx&preset=node

Steps to Reproduce the Bug or Issue

❗ Navigating via Links works correctly, so you need to directly visit the URL.

• To directly to /about without the ending /.
• Observe loaders not running

Expected behavior

Loaders should run 👍🏼

Screenshots or Videos

No response

Platform

• TSR Version: 1.38.1

Additional context

No response

[schiller-manuel]

I added a beforeLoad

https://stackblitz.com/edit/tanstack-router-af56kj?file=src%2Fmain.tsx,src%2Froutes%2F__root.tsx,src%2Froutes%2Fabout.tsx&preset=node

Accessing about/ works as expected:

beforeLoad foo
loader foo

but accessing about without the trailing slash causes the following error in loader:

Cannot read properties of undefined (reading 'foo')

[schiller-manuel]

this will be fixed by #1907

reproducer with the pre-release package: https://stackblitz.com/edit/tanstack-router-tlpd87?file=src%2Fmain.tsx,src%2Froutes%2F__root.tsx,src%2Froutes%2Fabout.tsx&preset=node