fix(fs-routes): throw error if routes directory is missing

[GuptaSiddhant]

The flatRoutes function is supposed to throw error if the routesDir does not exist. But due to a type, it was checking for rootRoute again and throwing error regarding missing routesDir.

Fixed the typo and couple of tests to check for correct error to be thrown in both scenarios.

[changeset-bot]

🦋 Changeset detected

Latest commit: 7e52bc4

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 11 packages

Name	Type
@react-router/fs-routes	Patch
create-react-router	Patch
react-router	Patch
react-router-dom	Patch
@react-router/architect	Patch
@react-router/cloudflare	Patch
@react-router/dev	Patch
@react-router/express	Patch
@react-router/node	Patch
@react-router/remix-routes-option-adapter	Patch
@react-router/serve	Patch

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[markdalgleish]

Thanks for the PR!

[github-actions]

🤖 Hello there,

We just published version 7.1.0-pre.0 which includes this pull request. If you'd like to take it for a test run please try it out and let us know what you think!

Thanks!

[github-actions]

🤖 Hello there,

We just published version 7.1.0 which includes this pull request. If you'd like to take it for a test run please try it out and let us know what you think!

Thanks!

[github-actions]

🤖 Hello there,

We just published version 6.28.2-pre.0 which includes this pull request. If you'd like to take it for a test run please try it out and let us know what you think!

Thanks!