chore: output blank css files to avoid broken builds (#1724)

packages/netlify-cms/package.json

@@ -45,6 +45,7 @@
     "netlify-cms-widget-text": "^2.0.5"
   },
   "devDependencies": {
+    "copy-webpack-plugin": "^4.5.2",
     "cross-env": "^5.2.0",
     "friendly-errors-webpack-plugin": "^1.7.0",
     "webpack": "^4.16.1",

packages/netlify-cms/shims/cms.css

@@ -0,0 +1,5 @@
+/**
+ * Netlify CMS 2.0 moved from static CSS to CSS-in-JS. Some site builds are configured to look
+ * for `cms.css`, and will break when it's missing, so we're putting out this blank file to help.
+ * We'll eventually remove it, so please update your build to not require it.
+ */

packages/netlify-cms/webpack.config.js

@@ -1,6 +1,7 @@
 const path = require('path');
 const webpack = require('webpack');
 const FriendlyErrorsWebpackPlugin = require('friendly-errors-webpack-plugin');
+const CopyWebpackPlugin = require('copy-webpack-plugin');
 const pkg = require('./package.json');
 const { plugins } = require('../../scripts/webpack');
 const coreWebpackConfig = require('../netlify-cms-core/webpack.config.js');
@@ -24,6 +25,7 @@ const baseConfig = {
         messages: ['Netlify CMS is now running at http://localhost:8080'],
       },
     }),
+    new CopyWebpackPlugin([{ from: '../shims/cms.css', to: 'dist/' }]),
   ],
   devServer: {
     contentBase: '../../dev-test',
@@ -44,7 +46,7 @@ if (isProduction) {
      */
     {
       ...baseConfig,
-      entry: [path.join(__dirname, 'scripts/deprecate-old-dist.js'), baseConfig.entry],
+      entry: [path.join(__dirname, 'shims/deprecate-old-dist.js'), baseConfig.entry],
       output: {
         ...baseConfig.output,
         filename: 'dist/cms.js',