resolve race condition when creating rd.json

scripts/build.js

@@ -13,14 +13,9 @@ process.on('unhandledRejection', err => {
     throw err;
 });
 
-// create radar
-
-require('../bin/tasks/radarjson').radarJsonGenerator()
-
 // Ensure environment variables are read.
 require('../config/env');
 
-
 const path = require('path');
 const chalk = require('react-dev-utils/chalk');
 const fs = require('fs-extra');
@@ -54,8 +49,9 @@ const config = configFactory('production');
 
 // We require that you explicitly set browsers and do not fall back to
 // browserslist defaults.
-const { checkBrowsers } = require('react-dev-utils/browsersHelper');
-checkBrowsers(paths.appPath, isInteractive)
+const {checkBrowsers} = require('react-dev-utils/browsersHelper');
+require('../bin/tasks/radarjson').radarJsonGenerator()
+    .then(checkBrowsers(paths.appPath, isInteractive))
     .then(() => {
         // First, read the current file sizes in build directory.
         // This lets us display how much they changed later.
@@ -71,7 +67,7 @@ checkBrowsers(paths.appPath, isInteractive)
         return build(previousFileSizes);
     })
     .then(
-    ({ stats, previousFileSizes, warnings }) => {
+        ({stats, previousFileSizes, warnings}) => {
             if (warnings.length) {
                 console.log(chalk.yellow('Compiled with warnings.\n'));
                 console.log(warnings.join('\n\n'));
@@ -134,6 +130,7 @@ checkBrowsers(paths.appPath, isInteractive)
         process.exit(1);
     });
 
+
 // Create the production build and print the deployment instructions.
 function build(previousFileSizes) {
     // We used to support resolving modules according to `NODE_PATH`.
@@ -174,7 +171,7 @@ function build(previousFileSizes) {
                 });
             } else {
                 messages = formatWebpackMessages(
-          stats.toJson({ all: false, warnings: true, errors: true })
+                    stats.toJson({all: false, warnings: true, errors: true})
                 );
             }
             if (messages.errors.length) {
@@ -215,3 +212,4 @@ function copyPublicFolder() {
         filter: file => file !== paths.appHtml,
     });
 }
+