fix(i18n): fallback on missing plural translation (#860)

Author: BobbieGoede

config/i18n.ts

@@ -78,6 +78,26 @@ export const countryLocaleVariants: Record<string, (LocaleObjectData & { country
     ],*/
 }
 
+function createPluralRule(locale: string, mapping: Record<string, number>) {
+  return (choice: number, choicesLength: number) => {
+    const name = new Intl.PluralRules(locale).select(choice)
+    const plural = mapping[name] || 0
+
+    // In case translation doesn't have all plural forms, use the last available form
+    if (plural > choicesLength - 1) {
+      if (import.meta.dev) {
+        // oxlint-disable-next-line no-console -- warn logging
+        console.warn(
+          `Plural form index ${plural} for choice ${choice} exceeds available forms ${choicesLength} for locale ${locale}.`,
+        )
+      }
+      return choicesLength - 1
+    }
+
+    return plural
+  }
+}
+
 const locales: (LocaleObjectData | (Omit<LocaleObjectData, 'code'> & { code: string }))[] = [
   {
     code: 'en',
@@ -89,10 +109,7 @@ const locales: (LocaleObjectData | (Omit<LocaleObjectData, 'code'> & { code: str
     file: 'ar.json',
     name: 'العربية',
     dir: 'rtl',
-    pluralRule: (choice: number) => {
-      const name = new Intl.PluralRules('ar-EG').select(choice)
-      return { zero: 0, one: 1, two: 2, few: 3, many: 4, other: 5 }[name]
-    },
+    pluralRule: createPluralRule('ar-EG', { zero: 0, one: 1, two: 2, few: 3, many: 4, other: 5 }),
   },
   {
     code: 'az-AZ',
@@ -148,10 +165,7 @@ const locales: (LocaleObjectData | (Omit<LocaleObjectData, 'code'> & { code: str
     code: 'hu-HU',
     file: 'hu-HU.json',
     name: 'Magyar',
-    pluralRule: (choice: number) => {
-      const name = new Intl.PluralRules('hu-HU').select(choice)
-      return { zero: 0, one: 0, two: 1, few: 1, many: 1, other: 1 }[name]
-    },
+    pluralRule: createPluralRule('hu-HU', { zero: 0, one: 0, two: 1, few: 1, many: 1, other: 1 }),
   },
   {
     code: 'zh-CN',
@@ -197,21 +211,13 @@ const locales: (LocaleObjectData | (Omit<LocaleObjectData, 'code'> & { code: str
     code: 'ru-RU',
     file: 'ru-RU.json',
     name: 'Русский',
-    pluralRule: (choice: number) => {
-      const name = new Intl.PluralRules('ru-RU').select(choice)
-      return { zero: 2, one: 0, two: 1, few: 1, many: 2, other: 3 }[name]
-    },
+    pluralRule: createPluralRule('ru-RU', { zero: 2, one: 0, two: 1, few: 1, many: 2, other: 3 }),
   },
   {
     code: 'uk-UA',
     file: 'uk-UA.json',
     name: 'Українська',
-    pluralRule: (choice: number) => {
-      if (choice === 0) return 0
-
-      const name = new Intl.PluralRules('uk-UA').select(choice)
-      return { zero: 0, one: 1, two: 0, few: 2, many: 3, other: 4 }[name]
-    },
+    pluralRule: createPluralRule('uk-UA', { zero: 0, one: 1, two: 0, few: 2, many: 3, other: 4 }),
   },
   /*{
       code: 'ru-RU',
@@ -226,10 +232,7 @@ const locales: (LocaleObjectData | (Omit<LocaleObjectData, 'code'> & { code: str
     code: 'cs-CZ',
     file: 'cs-CZ.json',
     name: 'Čeština',
-    pluralRule: (choice: number) => {
-      const name = new Intl.PluralRules('cs-CZ').select(choice)
-      return { zero: 2, one: 0, two: 1, few: 1, many: 2, other: 2 }[name]
-    },
+    pluralRule: createPluralRule('cs-CZ', { zero: 2, one: 0, two: 1, few: 1, many: 2, other: 2 }),
   } /*
     {
       code: 'pl-PL',
@@ -287,12 +290,7 @@ const locales: (LocaleObjectData | (Omit<LocaleObjectData, 'code'> & { code: str
     code: 'pl-PL',
     file: 'pl-PL.json',
     name: 'Polski',
-    pluralRule: (choice: number) => {
-      if (choice === 0) return 0
-
-      const name = new Intl.PluralRules('pl-PL').select(choice)
-      return { zero: 0, one: 1, two: 0, few: 2, many: 3, other: 4 }[name]
-    },
+    pluralRule: createPluralRule('pl-PL', { zero: 0, one: 1, two: 0, few: 2, many: 3, other: 4 }),
   },
   {
     code: 'pt-BR',