feat: add MergeError calss

packages/webpack-cli/lib/groups/ConfigGroup.js

@@ -4,7 +4,7 @@ const { extensions } = require('interpret');
 const webpackMerge = require('webpack-merge');
 const GroupHelper = require('../utils/GroupHelper');
 const rechoir = require('rechoir');
-const logger = require('../utils/logger');
+const MergeError = require('../utils/errors/MergeError');
 
 // Order defines the priority, in increasing order
 // example - config file lookup will be in order of .webpack/webpack.config.development.js -> webpack.config.development.js -> webpack.config.js
@@ -174,8 +174,7 @@ class ConfigGroup extends GroupHelper {
             const newConfigPath = this.resolveFilePath(merge);
 
             if (!newConfigPath) {
-                logger.error("The supplied merge config doesn't exist.");
-                process.exit(1);
+                throw new MergeError("The supplied merge config doesn't exist.");
             }
 
             const configFiles = getConfigInfoFromFileName(newConfigPath);

packages/webpack-cli/lib/utils/errors/MergeError.js

@@ -0,0 +1,10 @@
+class MergeError extends Error {
+    constructor(message) {
+        super(message);
+        this.name = 'MergeError';
+        // No need to show stack trace for known errors
+        this.stack = '';
+    }
+}
+
+module.exports = MergeError;

test/merge/config-absent/merge-config-absent.test.js

@@ -13,7 +13,7 @@ describe('merge flag configuration', () => {
         // Since the process will exit, nothing on stdout
         expect(stdout).toBeFalsy();
         // Confirm that the user is notified
-        expect(stderr).toContain(`[webpack-cli] The supplied merge config doesn't exist.`);
+        expect(stderr).toContain(`MergeError: The supplied merge config doesn't exist.`);
         // Default config would be used
         expect(fs.existsSync(join(__dirname, './dist/merged.js'))).toBeFalsy();
         // Since the process will exit so no compilation will be done