Fixes switching the localization language back to the default #15444

[Zebsterpasha]

What it does

Fixes switching the localization language back to the default #15444

How to test

1. Launch IDE
2. Press F1
3. Configure Display Language to something other than default
4. IDE will reboot
5. Make sure getNlsConfig() returns the correct language
   

   theia/packages/plugin-ext/src/hosted/node/hosted-plugin-process.ts

   Line 181 in b767004

   env['VSCODE_NLS_CONFIG'] = JSON.stringify(this.localizationService.getNlsConfig());

6. Switch the language to the default language (e.g. English)
7. getNlsConfig() will return the default language (breakpoint from point 5). Before the fix, it returned the previous language instead of the default language.

Follow-ups

Breaking changes

• This PR introduces breaking changes and requires careful review. If yes, the breaking changes section in the changelog has been updated.

Attribution

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

[martin-fleck-at]

Hi @Zebsterpasha,

Thank you for your PR! It seems that this change was introduced as part of #13134 as an optimization:

Update I18nPreloadContribution to ensure that we only load the localizations from the back end if the current locale is not equal to the default locale. This fixes an issue where we unnecessarily queried the localization server in the preload step if the locale is explicitly set to "en". (This happens for instance if you change the display language and then switch back to english).

However, it seems that due to that we are missing the setCurrentLanguage call that the server is making in the backend when we load the localizations:

theia/packages/core/src/node/i18n/localization-server.ts

Line 49 in ccc9f3e

this.localizationProvider.setCurrentLanguage(languageId);

@tortmayr Do you remember if there was any issue with loading localizations for the default language in particular? It seems to me that loading them should be quite fast anyways and I don't see why we would never want to load for the default locale as other localizations may have been added. Unless there is a good reason for this, I'm inclined to accept this PR (as soon as the CI is happy as well).

[tortmayr]

@tortmayr Do you remember if there was any issue with loading localizations for the default language in particular? It seems to me that loading them should be quite fast anyways and I don't see why we would never want to load for the default locale as other localizations may have been added. Unless there is a good reason for this, I'm inclined to accept this PR (as soon as the CI is happy as well).

I don't recall exactly. I think it gave a slight performance boost when using the default locale but nothing to significant.
Anyways, since there are issues with it we should accept this PR.
If we encounter significant performance degradation (witch I don't expect) we can handle this in a follow-up.

[martin-fleck-at]

Alright, then I'm accepting this PR. However, there seems to be an issue in the CI that seems unrelated to me: https://github.com/eclipse-theia/theia/actions/runs/14401863140/job/40497162158?pr=15445#step:7:1007. @JonasHelming Do you know whether there is a known issue in the CI?

[JonasHelming]

@martin-fleck-at Yes it is known