fix(gatsby): don't show error for proper redirects

[mnurik]

Description

Changed If statement for showing error message in Development mode, that if there is no such page redirect was intentional.

Related Issues

Fixes #18665

[pieh]

I think adding test case for redirects (one that overlap with existing page, and one that tries to redirect from non-existing page) in https://github.com/gatsbyjs/gatsby/tree/master/e2e-tests/development-runtime would help:

• with establishing how this work
• making sure we don't introduce regressions

[pvdz]

@mnurik (Github says you requested a review but I don't see new commits and @pieh's suggestion seems a good way forward. The tests will show us the way. And if you're correct then the current system is broken anyways so it'll be an improvement where a test would be really good to have anyways. Let me know if I missed anything?)

[mnurik]

@pieh @pvdz I have added e2e tests for redirect one that overlap with existing page, and one that tries to redirect from non-existing page. I couldn't find a way to write tests to check what console errors we have with Cypress.

[pvdz]

(Triggered a rebase to get the tests passed a breaking commit)

[pieh]

Looks good, thanks @mnurik!

edge case found

code was iterated on

[pvdz]

@mnurik Hi :) Can you please let us know if you're still working on this? I know there's been a lot of back-and-forth but it has been open for a while and no update for over a month so would like to know. Perhaps we should put this PR in Draft mode? (Click "convert to draft" under the reviewers block at the top)

[mnurik]

@pvdz Hi, unfortunately I am not, as @pieh started take care of it, and he changed all the stuff, so I am less familiar with changes than him. So feel free to close it, either @pieh can create separate PR or fix this one.

[pieh]

I'll put this into draft mode for now, because I don't remember status of it - the e2e tests for redirects we added seems to be passing, but also need to keep in mind the tests I added look pretty weird when I look at them right now (and also noted in the comments around them) and I'm not 100% confident they are actually correctly asseting things or not

[pieh]

Uff, thanks for patience on this. I finished this yesterday and turned out the problems with 404 existing or not were fixed in different PR since this one was opened ( likely in #18051 ) and we just got back to initial code change (+bunch of testing code)

[gatsbot]

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