Bug/v2/reduce console pollution (#4212)

# Description of Changes

<!--

Fixes the issues with I18 that were causing lots of console errors.
Fixes mime type error

Closes #(issue_number)
-->

---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

---------

Signed-off-by: dependabot[bot] <[email protected]>
Signed-off-by: stirlingbot[bot] <stirlingbot[bot]@users.noreply.github.com>
Co-authored-by: Ludy <[email protected]>
Co-authored-by: Dario Ghunney Ware <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: EthanHealy01 <[email protected]>
Co-authored-by: Ethan <[email protected]>
Co-authored-by: Anthony Stirling <[email protected]>
Co-authored-by: stirlingbot[bot] <195170888+stirlingbot[bot]@users.noreply.github.com>
Co-authored-by: albanobattistella <[email protected]>

frontend/src/i18n.ts

@@ -5,6 +5,7 @@ import Backend from 'i18next-http-backend';
 
 // Define supported languages (based on your existing translations)
 export const supportedLanguages = {
+  'en': 'English',
   'en-GB': 'English (UK)',
   'en-US': 'English (US)',
   'ar-AR': 'العربية',
@@ -57,26 +58,42 @@ i18n
   .use(initReactI18next)
   .init({
     fallbackLng: 'en-GB',
+    supportedLngs: Object.keys(supportedLanguages),
+    nonExplicitSupportedLngs: false,
     debug: process.env.NODE_ENV === 'development',
-    
+
+    // Ensure synchronous loading to prevent timing issues
+    initImmediate: false,
+
     interpolation: {
       escapeValue: false, // React already escapes values
     },
-    
+
     backend: {
-      loadPath: '/locales/{{lng}}/{{ns}}.json',
+      loadPath: (lngs: string[], namespaces: string[]) => {
+        // Map 'en' to 'en-GB' for loading translations
+        const lng = lngs[0] === 'en' ? 'en-GB' : lngs[0];
+        return `/locales/${lng}/${namespaces[0]}.json`;
+      },
     },
-    
+
     detection: {
       order: ['localStorage', 'navigator', 'htmlTag'],
       caches: ['localStorage'],
+      convertDetectedLanguage: (lng: string) => lng === 'en' ? 'en-GB' : lng,
     },
-    
+
     react: {
-      useSuspense: false, // Set to false to avoid suspense issues with SSR
+      useSuspense: true, // Enable suspense to prevent premature rendering
+      bindI18n: 'languageChanged loaded',
+      bindI18nStore: 'added removed',
+      transEmptyNodeValue: '', // Return empty string for missing keys instead of key name
+      transSupportBasicHtmlNodes: true,
+      transKeepBasicHtmlNodesFor: ['br', 'strong', 'i', 'p'],
     },
   });
 
+
 // Set document direction based on language
 i18n.on('languageChanged', (lng) => {
   const isRTL = rtlLanguages.includes(lng);
@@ -84,4 +101,4 @@ i18n.on('languageChanged', (lng) => {
   document.documentElement.lang = lng;
 });
 
-export default i18n;
+export default i18n;