fix(ivy): ngcc should not fail on invalid package.json (#26539)

Some package.json files may have invalid JSON, for example package.json blueprints from `@schematics/angular` (see https://github.com/angular/angular-cli/blob/master/packages/schematics/angular/workspace/files/package.json).

This makes ngcc more resilient, by simpling logging a warning if an error is encountered, instead of failing as it does right now.

PR Close #26539

packages/compiler-cli/src/ngcc/src/packages/entry_point.ts

@@ -50,6 +50,21 @@ interface EntryPointPackageJson {
   typings?: string;  // TypeScript .d.ts files
 }
 
+/**
+ * Parses the JSON from a package.json file.
+ * @param packageJsonPath the absolute path to the package.json file.
+ * @returns JSON from the package.json file if it is valid, `null` otherwise.
+ */
+function loadEntryPointPackage(packageJsonPath: string): {[key: string]: any}|null {
+  try {
+    return JSON.parse(fs.readFileSync(packageJsonPath, 'utf8'));
+  } catch (e) {
+    // We may have run into a package.json with unexpected symbols
+    console.warn(`Failed to read entry point info from ${packageJsonPath} with error ${e}.`);
+    return null;
+  }
+}
+
 /**
  * Try to get entry point info from the given path.
  * @param pkgPath the absolute path to the containing npm package
@@ -62,6 +77,11 @@ export function getEntryPointInfo(pkgPath: string, entryPoint: string): EntryPoi
     return null;
   }
 
+  const entryPointPackageJson = loadEntryPointPackage(packageJsonPath);
+  if (!entryPointPackageJson) {
+    return null;
+  }
+
   // If there is `esm2015` then `es2015` will be FESM2015, otherwise ESM2015.
   // If there is `esm5` then `module` will be FESM5, otherwise it will be ESM5.
   const {
@@ -75,8 +95,7 @@ export function getEntryPointInfo(pkgPath: string, entryPoint: string): EntryPoi
     esm2015,
     esm5,
     main
-  }: EntryPointPackageJson = JSON.parse(fs.readFileSync(packageJsonPath, 'utf8'));
+  } = entryPointPackageJson;
-
   // Minimum requirement is that we have typings and one of esm2015 or fesm2015 formats.
   if (!typings || !(fesm2015 || esm2015)) {
     return null;

packages/compiler-cli/src/ngcc/test/packages/entry_point_spec.ts

@@ -78,6 +78,11 @@ describe('getEntryPointInfo()', () => {
       umd: `/some_package/material_style/bundles/material_style.umd.js`,
     });
   });
+
+  it('should return null if the package.json is not valid JSON', () => {
+    const entryPoint = getEntryPointInfo('/some_package', '/some_package/unexpected_symbols');
+    expect(entryPoint).toBe(null);
+  });
 });
 
 function createMockFileSystem() {
@@ -115,8 +120,15 @@ function createMockFileSystem() {
           "module": "./esm5/material_style.es5.js",
           "es2015": "./esm2015/material_style.js"
         }`,
-        'material_style.metadata.json': 'some meta data'
+        'material_style.metadata.json': 'some meta data',
-      }
+      },
+      'unexpected_symbols': {
+        // package.json might not be a valid JSON
+        // for example, @schematics/angular contains a package.json blueprint
+        // with unexpected symbols
+        'package.json':
+            '{"devDependencies": {<% if (!minimal) { %>"@types/jasmine": "~2.8.8" <% } %>}}',
+      },
     }
   });
 }