fix: don't use deprecated JSON parser

src/ng-add.ts

@@ -1,11 +1,29 @@
-import { JsonParseMode, parseJson } from '@angular-devkit/core';
+import { ParseError, parse, printParseErrorCode } from 'jsonc-parser';
+import { JsonValue } from '@angular-devkit/core';
 import {
   SchematicContext,
   SchematicsException,
   Tree
 } from '@angular-devkit/schematics';
 import { Workspace } from './interfaces';
 
+export function parseJsonFile(json: string): JsonValue {
+  const errors: ParseError[] = [];
+  const content = parse(json, errors, { allowTrailingComma: true });
+
+  if (errors.length) {
+    const { error, offset } = errors[0];
+    throw new Error(
+      `Failed to parse as JSON AST Object. ${printParseErrorCode(
+        error,
+      )} at location: ${offset}.`,
+    );
+  }
+
+  return content;
+}
+
+
 function getWorkspace(host: Tree): { path: string; workspace: Workspace } {
   const possibleFiles = ['/angular.json', '/.angular.json'];
   const path = possibleFiles.filter(path => host.exists(path))[0];
@@ -18,7 +36,7 @@ function getWorkspace(host: Tree): { path: string; workspace: Workspace } {
 
   let workspace: Workspace;
   try {
-    workspace = (parseJson(content, JsonParseMode.Loose) as {}) as Workspace;
+    workspace = (parseJsonFile(content) as {}) as Workspace;
   } catch (e) {
     throw new SchematicsException(`Could not parse angular.json: ` + e.message);
   }

src/package.json

@@ -74,7 +74,8 @@
   "dependencies": {
     "commander": "^3.0.0-0",
     "fs-extra": "^9.0.1",
-    "gh-pages": "^3.1.0"
+    "gh-pages": "^3.1.0",
+    "jsonc-parser": "^3.0.0"
   },
   "husky": {
     "hooks": {