Increment importLoaders for rulesets where there's a preprocessor (fixes #7919)

Author: joshhunt

packages/react-scripts/config/webpack.config.js

@@ -141,6 +141,8 @@ module.exports = function(webpackEnv) {
             sourceMap: true,
           },
         }
+        // ** STOP ** Are you adding a new loader after css-loader?
+        // Make sure to increment importLoaders appropriately where getStyleLoaders is called.
       );
     }
     return loaders;
@@ -528,7 +530,7 @@ module.exports = function(webpackEnv) {
               exclude: sassModuleRegex,
               use: getStyleLoaders(
                 {
-                  importLoaders: 2,
+                  importLoaders: 3,
                   sourceMap: isEnvProduction && shouldUseSourceMap,
                 },
                 'sass-loader'
@@ -545,7 +547,7 @@ module.exports = function(webpackEnv) {
               test: sassModuleRegex,
               use: getStyleLoaders(
                 {
-                  importLoaders: 2,
+                  importLoaders: 3,
                   sourceMap: isEnvProduction && shouldUseSourceMap,
                   modules: {
                     getLocalIdent: getCSSModuleLocalIdent,