chore(cr): add shortcut function applyRuleConfigurationCallback

Author: Kocal

lib/config-generator.js

@@ -221,6 +221,14 @@ class ConfigGenerator {
     }
 
     buildRulesConfig() {
+        const applyRuleConfigurationCallback = (name, defaultRules) => {
+            if (!(name in this.webpackConfig.loaderConfigurationCallbacks)) {
+                throw new Error(`Loader "${name}" is not configurable. Valid loaders are "${Object.keys(this.webpackConfig.loaderConfigurationCallbacks).join('", "')}".`);
+            }
+
+            return applyOptionsCallback(this.webpackConfig.loaderConfigurationCallbacks[name], defaultRules);
+        };
+
         let rules = [
             {
                 // match .js and .jsx
@@ -357,7 +365,7 @@ class ConfigGenerator {
         }
 
         if (this.webpackConfig.useEslintLoader) {
-            rules.push(applyOptionsCallback(this.webpackConfig.loaderConfigurationCallbacks['eslint'], {
+            rules.push(applyRuleConfigurationCallback('eslint', {
                 test: /\.jsx?$/,
                 loader: 'eslint-loader',
                 exclude: /node_modules/,