refactor(@angular-devkit/build-angular): improve i18n project option validation

The `i18n` project field is used to configure i18n behavior for a project.
The validation code has been reorganized to use two helper functions to
centralize the type validation and exception throwing. This reduces the complexity
of the analysis code as well as removing the need to rely on `@angular-devkit/core`.

Author: clydin

packages/angular_devkit/build_angular/src/utils/i18n-options.ts

@@ -7,11 +7,10 @@
  */
 
 import { BuilderContext } from '@angular-devkit/architect';
-import { json } from '@angular-devkit/core';
-import fs from 'fs';
-import module from 'module';
-import os from 'os';
-import path from 'path';
+import fs from 'node:fs';
+import { createRequire } from 'node:module';
+import os from 'node:os';
+import path from 'node:path';
 import { Schema as BrowserBuilderSchema, I18NTranslation } from '../builders/browser/schema';
 import { Schema as ServerBuilderSchema } from '../builders/server/schema';
 import { readTsconfig } from '../utils/read-tsconfig';
@@ -43,7 +42,7 @@ export interface I18nOptions {
 }
 
 function normalizeTranslationFileOption(
-  option: json.JsonValue,
+  option: unknown,
   locale: string,
   expectObjectInError: boolean,
 ): string[] {
@@ -65,14 +64,25 @@ function normalizeTranslationFileOption(
   throw new Error(errorMessage);
 }
 
+function ensureObject(value: unknown, name: string): asserts value is Record<string, unknown> {
+  if (!value || typeof value !== 'object' || Array.isArray(value)) {
+    throw new Error(`Project ${name} field is malformed. Expected an object.`);
+  }
+}
+
+function ensureString(value: unknown, name: string): asserts value is string {
+  if (typeof value !== 'string') {
+    throw new Error(`Project ${name} field is malformed. Expected a string.`);
+  }
+}
+
 export function createI18nOptions(
-  metadata: json.JsonObject,
+  projectMetadata: { i18n?: unknown },
   inline?: boolean | string[],
 ): I18nOptions {
-  if (metadata.i18n !== undefined && !json.isJsonObject(metadata.i18n)) {
-    throw new Error('Project i18n field is malformed. Expected an object.');
-  }
-  metadata = metadata.i18n || {};
+  const { i18n: metadata = {} } = projectMetadata;
+
+  ensureObject(metadata, 'i18n');
 
   const i18n: I18nOptions = {
     inlineLocales: new Set<string>(),
@@ -86,24 +96,23 @@ export function createI18nOptions(
 
   let rawSourceLocale;
   let rawSourceLocaleBaseHref;
-  if (json.isJsonObject(metadata.sourceLocale)) {
-    rawSourceLocale = metadata.sourceLocale.code;
-    if (
-      metadata.sourceLocale.baseHref !== undefined &&
-      typeof metadata.sourceLocale.baseHref !== 'string'
-    ) {
-      throw new Error('Project i18n sourceLocale baseHref field is malformed. Expected a string.');
-    }
-    rawSourceLocaleBaseHref = metadata.sourceLocale.baseHref;
-  } else {
+  if (typeof metadata.sourceLocale === 'string') {
     rawSourceLocale = metadata.sourceLocale;
-  }
+  } else if (metadata.sourceLocale !== undefined) {
+    ensureObject(metadata.sourceLocale, 'i18n sourceLocale');
 
-  if (rawSourceLocale !== undefined) {
-    if (typeof rawSourceLocale !== 'string') {
-      throw new Error('Project i18n sourceLocale field is malformed. Expected a string.');
+    if (metadata.sourceLocale.code !== undefined) {
+      ensureString(metadata.sourceLocale.code, 'i18n sourceLocale code');
+      rawSourceLocale = metadata.sourceLocale.code;
+    }
+
+    if (metadata.sourceLocale.baseHref !== undefined) {
+      ensureString(metadata.sourceLocale.baseHref, 'i18n sourceLocale baseHref');
+      rawSourceLocaleBaseHref = metadata.sourceLocale.baseHref;
     }
+  }
 
+  if (rawSourceLocale !== undefined) {
     i18n.sourceLocale = rawSourceLocale;
     i18n.hasDefinedSourceLocale = true;
   }
@@ -113,16 +122,17 @@ export function createI18nOptions(
     baseHref: rawSourceLocaleBaseHref,
   };
 
-  if (metadata.locales !== undefined && !json.isJsonObject(metadata.locales)) {
-    throw new Error('Project i18n locales field is malformed. Expected an object.');
-  } else if (metadata.locales) {
+  if (metadata.locales !== undefined) {
+    ensureObject(metadata.locales, 'i18n locales');
+
     for (const [locale, options] of Object.entries(metadata.locales)) {
       let translationFiles;
       let baseHref;
-      if (json.isJsonObject(options)) {
+      if (options && typeof options === 'object' && 'translation' in options) {
         translationFiles = normalizeTranslationFileOption(options.translation, locale, false);
 
-        if (typeof options.baseHref === 'string') {
+        if ('baseHref' in options) {
+          ensureString(options.baseHref, `i18n locales ${locale} baseHref`);
           baseHref = options.baseHref;
         }
       } else {
@@ -181,7 +191,7 @@ export async function configureI18nBuild<T extends BrowserBuilderSchema | Server
 
   const projectRoot = path.join(context.workspaceRoot, (metadata.root as string) || '');
   // The trailing slash is required to signal that the path is a directory and not a file.
-  const projectRequire = module.createRequire(projectRoot + '/');
+  const projectRequire = createRequire(projectRoot + '/');
   const localeResolver = (locale: string) =>
     projectRequire.resolve(path.join(LOCALE_DATA_BASE_MODULE, locale));