Passwordless Auth Core Profiler - Display an error when the requested user is unknown

[moon0326]

Related to p1732259352777309-slack-C01SFMVEYAK

Proposed Changes

• When the requested user is unknown, display an error instead of sending the user to the magic login page.

Why are these changes being made?

• To fix a bug with the new passwordless Jetpack connection.

Testing Instructions

1. Checkout this branch and run yarn start
2. Open this link in an incognito session.
3. Enter an unknown username.
4. You should see an error message.

Pre-merge Checklist

• [ ] Has the general commit checklist been followed? (PCYsg-hS-p2)
• [ ] Have you written new tests for your changes?
• [ ] Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• [ ] Have you checked for TypeScript, React or other console errors?
• [ ] Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• [ ] Have we added the "[Status] String Freeze" label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
  • [ ] For UI changes, have we tested the change in various languages (for example, ES, PT, FR, or DE)? The length of text and words vary significantly between languages.
• [ ] For changes affecting Jetpack: Have we added the "[Status] Needs Privacy Updates" label if this pull request changes what data or activity we track or use (p4TIVU-aUh-p2)?

[github-actions[bot]]

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[matticbot]

Here is how your PR affects size of JS and CSS bundles shipped to the user's browser:

App Entrypoints (~5 bytes added 📈 [gzipped])

``` name parsed_size gzip_size entry-login +68 B (+0.0%) +5 B (+0.0%) ``` Common code that is always downloaded and parsed every time the app is loaded, no matter which route is used.

Sections (~6 bytes added 📈 [gzipped])

``` name parsed_size gzip_size jetpack-connect +68 B (+0.0%) +6 B (+0.0%) ``` Sections contain code specific for a given set of routes. Is downloaded and parsed only when a particular route is navigated to.

Async-loaded Components (~6 bytes added 📈 [gzipped])

``` name parsed_size gzip_size async-load-design-blocks +68 B (+0.0%) +6 B (+0.0%) ``` React components that are loaded lazily, when a certain part of UI is displayed for the first time.

Legend

What is parsed and gzip size?

**Parsed Size:** Uncompressed size of the JS and CSS files. This much code needs to be parsed and stored in memory. **Gzip Size:** Compressed size of the JS and CSS files. This much data needs to be downloaded over network.

Generated by performance advisor bot at iscalypsofastyet.com.