feat: allow empty package.json for 2ndary entries

src/lib/steps/package.ts

@@ -3,6 +3,7 @@ import { NgPackageConfig } from '../../ng-package.schema';
 import { NgPackageData, DEFAULT_BUILD_FOLDER } from '../model/ng-package-data';
 import { NgArtifacts } from '../model/ng-artifacts';
 import { copyFiles } from '../util/copy';
+import { tryReadJson } from '../util/json';
 import { readJson, writeJson, readdir, lstat, Stats } from 'fs-extra';
 import { merge, isArray } from 'lodash';
 import * as log from '../util/log';
@@ -172,17 +173,21 @@ async function readSecondaryPackage(rootPackage: NgPackageData, filePath: string
   const packageJsonFile = path.resolve(baseDirectory, 'package.json');
 
   let ngPackage: NgPackageConfig = await readNgPackageFile(ngPackageFile);
-  const packageJson = await readJson(packageJsonFile);
+  const packageJson: any = await tryReadJson(packageJsonFile);
 
   ngPackage = merge(ngPackage, packageJson.ngPackage, arrayMergeLogic);
+  if (!ngPackage.lib) {
+    ngPackage.lib = {};
+  }
+
   ngPackage.lib.externals = rootPackage.libExternals;
 
   return new NgPackageData(
     rootPackage.sourcePath,
     rootPackage.fullPackageName,
     rootPackage.destinationPath,
     baseDirectory,
-    ngPackage
+    rootPackage.libExternals
   );
 }
 

src/lib/util/json.ts

@@ -18,9 +18,23 @@ export async function modifyJsonFiles(globPattern: string, modifyFn: (jsonObj: a
 
   await Promise.all(
     fileNames.map(async (fileName: string): Promise<void> => {
-      const fileContent: any = await readJson(fileName);
+      const fileContent: any = await tryReadJson(fileName);
       const modified = modifyFn(fileContent);
       await writeJson(fileName, modified);
     }
   ));
 }
+
+/**
+ * Read json and don't throw if json parsing fails.
+ *
+ * @param filePath Path to the file which is parsed.
+ */
+export async function tryReadJson(filePath: string): Promise<any> {
+  try {
+    return await readJson(filePath);
+  } catch {
+    // this means the file was empty or not json, which is fine
+    return {};
+  }
+}