fix(@schematics/angular): provide more context on offending invalid JSON file

Closes: #18120
(cherry picked from commit 2039f28)

Author: alan-agius4

packages/schematics/angular/migrations/update-10/solution-style-tsconfig.ts

@@ -5,7 +5,7 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
-import { JsonAstNode, JsonAstString, JsonParseMode, dirname, join, normalize, parseJsonAst, resolve } from '@angular-devkit/core';
+import { JsonAstNode, JsonAstString, JsonParseMode, dirname, join, logging, normalize, parseJsonAst, resolve } from '@angular-devkit/core';
 import { DirEntry, Rule, chain } from '@angular-devkit/schematics';
 import { findPropertyInAstObject } from '../../utility/json-utils';
 import { getWorkspace } from '../../utility/workspace';
@@ -18,7 +18,7 @@ const SOLUTIONS_TS_CONFIG_HEADER = `/*
 */
 `;
 
-function* visitExtendedJsonFiles(directory: DirEntry): IterableIterator<[string, JsonAstString]> {
+function* visitExtendedJsonFiles(directory: DirEntry, logger: logging.LoggerApi): IterableIterator<[string, JsonAstString]> {
   for (const path of directory.subfiles) {
     if (!path.endsWith('.json')) {
       continue;
@@ -33,8 +33,16 @@ function* visitExtendedJsonFiles(directory: DirEntry): IterableIterator<[string,
     let jsonAst: JsonAstNode;
     try {
       jsonAst = parseJsonAst(content, JsonParseMode.Loose);
-    } catch {
-      throw new Error(`Invalid JSON AST Object (${path})`);
+    } catch (error) {
+      let jsonFilePath = `${join(directory.path, path)}`;
+      jsonFilePath = jsonFilePath.startsWith('/') ? jsonFilePath.substr(1) : jsonFilePath;
+
+      const msg = error instanceof Error ? error.message : error;
+      logger.warn(
+        `Failed to parse "${jsonFilePath}" as JSON AST Object. ${msg}\n` +
+        'If this is a TypeScript configuration file you will need to update the "extends" value manually.',
+      );
+      continue;
     }
 
     if (jsonAst.kind !== 'object') {
@@ -54,12 +62,12 @@ function* visitExtendedJsonFiles(directory: DirEntry): IterableIterator<[string,
       continue;
     }
 
-    yield* visitExtendedJsonFiles(directory.dir(path));
+    yield* visitExtendedJsonFiles(directory.dir(path), logger);
   }
 }
 
 function updateTsconfigExtendsRule(): Rule {
-  return host => {
+  return (host, context) => {
     if (!host.exists('tsconfig.json')) {
       return;
     }
@@ -68,7 +76,7 @@ function updateTsconfigExtendsRule(): Rule {
     host.rename('tsconfig.json', 'tsconfig.base.json');
 
     // Iterate over all tsconfig files and change the extends from 'tsconfig.json' 'tsconfig.base.json'
-    for (const [tsconfigPath, extendsAst] of visitExtendedJsonFiles(host.root)) {
+    for (const [tsconfigPath, extendsAst] of visitExtendedJsonFiles(host.root, context.logger)) {
       const tsConfigDir = dirname(normalize(tsconfigPath));
       if ('/tsconfig.json' !== resolve(tsConfigDir, normalize(extendsAst.value))) {
         // tsconfig extends doesn't refer to the workspace tsconfig path.

packages/schematics/angular/migrations/update-10/solution-style-tsconfig_spec.ts

@@ -120,4 +120,15 @@ describe('Migration to create "Solution Style" tsconfig', () => {
     const newTree = await schematicRunner.runSchematicAsync(schematicName, {}, tree).toPromise();
     expect(readJsonFile(newTree, 'src/tsconfig.json').extends).toEqual('./../tsconfig.base.json');
   });
+
+  it('should show warning with full path when parsing invalid JSON', async () => {
+    const logs: string[] = [];
+    schematicRunner.logger.subscribe(m => logs.push(m.message));
+
+    tree.create('src/invalid/error.json', '{ invalid }');
+    const newTree = await schematicRunner.runSchematicAsync(schematicName, {}, tree).toPromise();
+
+    expect(readJsonFile(newTree, 'src/tsconfig.tsc.json').extends).toEqual('./tsconfig.json');
+    expect(logs.join('\n')).toContain('Failed to parse "src/invalid/error.json" as JSON AST Object. Invalid JSON character');
+  });
 });