From e0a4a0991cdfccdaf18e7eb479f87bc2ee4e2e5f Mon Sep 17 00:00:00 2001
From: Alexander Akait <4567934+alexander-akait@users.noreply.github.com>
Date: Mon, 20 Mar 2023 02:46:47 +0300
Subject: [PATCH] fix: error message for missing default export in
 configuration (#3685)

---
 packages/webpack-cli/src/webpack-cli.ts          |  5 +++++
 test/build/config/named-export/mjs.test.js       | 16 ++++++++++++++++
 .../build/config/named-export/webpack.config.mjs |  1 +
 3 files changed, 22 insertions(+)
 create mode 100644 test/build/config/named-export/mjs.test.js
 create mode 100644 test/build/config/named-export/webpack.config.mjs

diff --git a/packages/webpack-cli/src/webpack-cli.ts b/packages/webpack-cli/src/webpack-cli.ts
index 777a811cb8f..c5ab34cd6bb 100644
--- a/packages/webpack-cli/src/webpack-cli.ts
+++ b/packages/webpack-cli/src/webpack-cli.ts
@@ -1772,6 +1772,11 @@ class WebpackCLI implements IWebpackCLI {
         process.exit(2);
       }
 
+      if (!options) {
+        this.logger.error(`Failed to load '${configPath}' config. Unable to find default export.`);
+        process.exit(2);
+      }
+
       if (Array.isArray(options)) {
         // reassign the value to assert type
         const optionsArray: ConfigOptions[] = options;
diff --git a/test/build/config/named-export/mjs.test.js b/test/build/config/named-export/mjs.test.js
new file mode 100644
index 00000000000..ab4336a35fc
--- /dev/null
+++ b/test/build/config/named-export/mjs.test.js
@@ -0,0 +1,16 @@
+const { run } = require("../../../utils/test-utils");
+
+describe("webpack cli", () => {
+  it("should support mjs config format", async () => {
+    const { exitCode, stderr } = await run(__dirname, ["-c", "webpack.config.mjs"], {
+      env: { WEBPACK_CLI_FORCE_LOAD_ESM_CONFIG: true },
+    });
+
+    if (/Error: Not supported/.test(stderr)) {
+      expect(exitCode).toBe(2);
+    } else {
+      expect(exitCode).toBe(2);
+      expect(stderr).toMatch(/Unable to find default export./);
+    }
+  });
+});
diff --git a/test/build/config/named-export/webpack.config.mjs b/test/build/config/named-export/webpack.config.mjs
new file mode 100644
index 00000000000..ee6a98eac9a
--- /dev/null
+++ b/test/build/config/named-export/webpack.config.mjs
@@ -0,0 +1 @@
+export let config = {};