From 4e1bd0decd8afe545ace9202073168ec21dade17 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juho=20Veps=C3=A4l=C3=A4inen?= <bebraw@gmail.com>
Date: Mon, 5 Jul 2021 14:27:02 +0300
Subject: [PATCH 1/2] fix(angular): Quit process after finishing a static build

I don't understand why `process.exit` is needed for this particular case
but it seems to fix the issue.

In order to be more safe, I also added a `try`/`catch` and in my own
testing that caught a ngcc locking issue I would have missed otherwise.

Closes #15227.
---
 app/angular/src/server/build.ts | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/app/angular/src/server/build.ts b/app/angular/src/server/build.ts
index d8abf06a4396..54d61f8c6318 100644
--- a/app/angular/src/server/build.ts
+++ b/app/angular/src/server/build.ts
@@ -1,4 +1,16 @@
 import { buildStatic } from '@storybook/core/server';
+import { logger } from '@storybook/node-logger';
 import options from './options';
 
-buildStatic(options);
+async function build() {
+  try {
+    await buildStatic(options);
+
+    // #15227
+    process.exit(0);
+  } catch (error) {
+    logger.error(error);
+  }
+}
+
+build();

From 9389325c80373d9cd96c2845d39e0b46ba2a7b16 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juho=20Veps=C3=A4l=C3=A4inen?= <bebraw@gmail.com>
Date: Wed, 7 Jul 2021 10:22:06 +0300
Subject: [PATCH 2/2] fix: Remember to close webpack compiler

It looks like this is the right way to go instead of `process.exit`.
---
 app/angular/src/server/build.ts   |  3 ---
 lib/builder-webpack5/src/index.ts | 23 +++++++++++++++++++----
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/app/angular/src/server/build.ts b/app/angular/src/server/build.ts
index 54d61f8c6318..fe1ed4fb11e3 100644
--- a/app/angular/src/server/build.ts
+++ b/app/angular/src/server/build.ts
@@ -5,9 +5,6 @@ import options from './options';
 async function build() {
   try {
     await buildStatic(options);
-
-    // #15227
-    process.exit(0);
   } catch (error) {
     logger.error(error);
   }
diff --git a/lib/builder-webpack5/src/index.ts b/lib/builder-webpack5/src/index.ts
index c1639be842c1..cec11f62cfbe 100644
--- a/lib/builder-webpack5/src/index.ts
+++ b/lib/builder-webpack5/src/index.ts
@@ -129,14 +129,19 @@ export const build: WebpackBuilder['build'] = async ({ options, startTime }) =>
   const config = await getConfig(options);
 
   return new Promise((succeed, fail) => {
-    webpackInstance(config).run((error, stats) => {
+    const compiler = webpackInstance(config);
+
+    compiler.run((error, stats) => {
       if (error || !stats || stats.hasErrors()) {
         logger.error('=> Failed to build the preview');
         process.exitCode = 1;
 
         if (error) {
           logger.error(error.message);
-          return fail(error);
+
+          compiler.close(() => fail(error));
+
+          return;
         }
 
         if (stats && (stats.hasErrors() || stats.hasWarnings())) {
@@ -145,7 +150,9 @@ export const build: WebpackBuilder['build'] = async ({ options, startTime }) =>
           errors.forEach((e) => logger.error(e.message));
           warnings.forEach((e) => logger.error(e.message));
 
-          return fail(stats);
+          compiler.close(() => fail(stats));
+
+          return;
         }
       }
 
@@ -154,7 +161,15 @@ export const build: WebpackBuilder['build'] = async ({ options, startTime }) =>
         stats.toJson({ warnings: true }).warnings.forEach((e) => logger.warn(e.message));
       }
 
-      return succeed(stats);
+      // https://webpack.js.org/api/node/#run
+      // #15227
+      compiler.close((closeErr) => {
+        if (closeErr) {
+          return fail(closeErr);
+        }
+
+        return succeed(stats);
+      });
     });
   });
 };