fix: depend on user's typescript

Previously, a user of ng-packagr could install an incompatible typescript version for ng-packagr. Prevent inadvertent typescript installs by depending on a user's typescript isntallation (peerDependencies). This should be/is non-breaking as any Angular project requires typescript as devDependency.

For Angular v4 support, please make sure to use an appropriate TypeScript version - following ng cli recommendation, this should be >= 2.3.4 and <2.4.0.

package.json

@@ -46,10 +46,12 @@
     "sorcery": "^0.10.0",
     "stylus": "^0.54.5",
     "ts-node": "^3.0.4",
-    "typescript": "^2.3.4",
     "uglify-js": "^3.0.7",
     "vinyl-fs": "^2.4.4"
   },
+  "peerDependencies": {
+    "typescript": "^2.3.4"
+  },
   "devDependencies": {
     "@angular/cdk": "^2.0.0-beta.11",
     "@angular/common": "^4.4.5",
@@ -78,6 +80,7 @@
     "rxjs": "^5.4.0",
     "sinon": "^4.0.0",
     "standard-version": "^4.0.0",
+    "typescript": "^2.3.4",
     "zone.js": "^0.8.10"
   },
   "private": true,

src/lib/util/json.ts

@@ -1,7 +1,8 @@
-const glob = require('glob')
+import * as glob from 'glob';
 import { readJson, writeJson } from 'fs-extra';
 import { promisify } from './promisify';
 import { debug } from './log';
+
 /**
  * Modifies a set of JSON files by invoking `modifyFn`
  *
@@ -33,8 +34,8 @@ export async function modifyJsonFiles(globPattern: string, modifyFn: (jsonObj: a
 export async function tryReadJson(filePath: string): Promise<any> {
   try {
     return await readJson(filePath);
-  } catch {
+  } catch (e) {
     // this means the file was empty or not json, which is fine
-    return {};
+    return Promise.resolve({});
   }
 }