Use async where possible to avoid .then() nesting

generator-jsonforms/package.json

@@ -15,13 +15,15 @@
     "custominstall": "npm run postinstall",
     "lint": "tslint --project tsconfig.json"
   },
+  "main": "./generators/app/index.js",
   "dependencies": {
     "@types/yeoman-generator": "^3.0.1",
     "chalk": "^2.4.2",
     "clear": "^0.1.0",
     "figlet": "^1.2.1",
     "jsonforms-react-seed": "git+https://[email protected]/eclipsesource/jsonforms-react-seed.git",
     "make-it-happen-react": "git+https://[email protected]/eclipsesource/make-it-happen-react.git",
+    "util": "^0.11.1",
     "validate-npm-package-name": "^3.0.0",
     "yeoman-generator": "^3.2.0"
   },

generator-jsonforms/src/generators/app/index.ts

@@ -9,6 +9,7 @@ const figlet = require('figlet');
 const validate = require('validate-npm-package-name');
 import { join, sep } from 'path';
 import { readFile, writeFile } from 'fs';
+import { promisify } from 'util';
 
 enum ProjectRepo {
   Example = 'make-it-happen-react',
@@ -20,6 +21,9 @@ enum Project {
   Seed = 'seed',
 }
 
+const readFileWithPromise = promisify(readFile);
+const writeFileWithPromise = promisify(writeFile);
+
 export class JsonformsGenerator extends Generator {
 
   project: string;
@@ -141,23 +145,22 @@ export class JsonformsGenerator extends Generator {
     this.log('installing');
     if (this.project === Project.Seed && this.name != null) {
       const packagePath = this.path + sep + 'package.json';
-      readFile(packagePath, 'utf8', (readError, data) => {
-
-        if ((readError != null) && readError.message) {
-          this.log(chalk.red(readError.message));
-          return;
-        }
-
-        const packageJson = JSON.parse(data);
-        packageJson.name = this.name;
-
-        writeFile(packagePath, JSON.stringify(packageJson, null, 2), writeError => {
-          if (writeError.message) {
-            this.log(chalk.red(writeError.message));
-            return;
-          }
-        });
-      });
+      let content = '';
+      try {
+        content = await readFileWithPromise(packagePath, 'utf8');
+      } catch (err) {
+        this.log(chalk.red(err.message));
+        return;
+      }
+      const packageJson = JSON.parse(content);
+      packageJson.name = this.name;
+
+      try {
+        await writeFileWithPromise(packagePath, JSON.stringify(packageJson, null, 2));
+      } catch (err) {
+        this.log(chalk.red(err.message));
+        return;
+      }
     }
 
     process.chdir(this.path);

jsonforms-tooling-common/package.json

@@ -20,6 +20,7 @@
     "ajv": "^6.5.5",
     "react": "^16.8.3",
     "redux": "^3.0.0",
+    "util": "^0.11.1",
     "chokidar": "^2.1.2",
     "yeoman-environment": "^2.3.4"
   },