fix(@angular/build): only issue invalid i18n config error for duplicate subPaths with inlined locales

The i18n configuration validation was incorrectly flagging errors for identical `subPaths` when both locales were not inlined within the same build. This was due to the validation not properly accounting for the inlining of locales.

This commit fixes this issue by ensuring that the validation only checks for duplicate `subPaths` when the locales are inlined.

Closes #29398

Author: alan-agius4

packages/angular/build/src/utils/i18n-options.ts

@@ -199,8 +199,24 @@ export function createI18nOptions(
     }
   }
 
-  // Check that subPaths are unique.
-  const localesData = Object.entries(i18n.locales);
+  if (inline === true) {
+    i18n.inlineLocales.add(i18n.sourceLocale);
+    Object.keys(i18n.locales).forEach((locale) => i18n.inlineLocales.add(locale));
+  } else if (inline) {
+    for (const locale of inline) {
+      if (!i18n.locales[locale] && i18n.sourceLocale !== locale) {
+        throw new Error(`Requested locale '${locale}' is not defined for the project.`);
+      }
+
+      i18n.inlineLocales.add(locale);
+    }
+  }
+
+  // Check that subPaths are unique only the locales that we are inlining.
+  const localesData = Object.entries(i18n.locales).filter(([locale]) =>
+    i18n.inlineLocales.has(locale),
+  );
+
   for (let i = 0; i < localesData.length; i++) {
     const [localeA, { subPath: subPathA }] = localesData[i];
 
@@ -215,19 +231,6 @@ export function createI18nOptions(
     }
   }
 
-  if (inline === true) {
-    i18n.inlineLocales.add(i18n.sourceLocale);
-    Object.keys(i18n.locales).forEach((locale) => i18n.inlineLocales.add(locale));
-  } else if (inline) {
-    for (const locale of inline) {
-      if (!i18n.locales[locale] && i18n.sourceLocale !== locale) {
-        throw new Error(`Requested locale '${locale}' is not defined for the project.`);
-      }
-
-      i18n.inlineLocales.add(locale);
-    }
-  }
-
   return i18n;
 }