fix: update to cssnano 5 (#357)

Author: ludofischer

package.json

@@ -44,7 +44,7 @@
     "jest": "^26.6.3",
     "less": "^3.12.2",
     "node-sass": "^5.0.0",
-    "postcss": "^8.1.14",
+    "postcss": "^8.2.7",
     "rollup": "^2.34.2",
     "stylus": "^0.54.8",
     "sugarss": "^3.0.3",
@@ -53,7 +53,7 @@
   "dependencies": {
     "chalk": "^4.1.0",
     "concat-with-sourcemaps": "^1.1.0",
-    "cssnano": "^4.1.10",
+    "cssnano": "^5.0.1",
     "import-cwd": "^3.0.0",
     "p-queue": "^6.6.2",
     "pify": "^5.0.0",
@@ -103,4 +103,4 @@
       "next"
     ]
   }
-}
+}

src/index.js

@@ -224,7 +224,7 @@ export default (options = {}) => {
       let { code, codeFileName, map, mapFileName } = getExtracted()
       // Perform cssnano on the extracted file
       if (postcssLoaderOptions.minimize) {
-        const cssOptions = postcssLoaderOptions.minimize
+        const cssOptions = {}
         cssOptions.from = codeFileName
         if (sourceMap === 'inline') {
           cssOptions.map = { inline: true }
@@ -233,7 +233,7 @@ export default (options = {}) => {
           cssOptions.to = codeFileName
         }
 
-        const result = await require('cssnano').process(code, cssOptions)
+        const result = await require('cssnano')(postcssLoaderOptions.minimize).process(code, cssOptions)
         code = result.css
 
         if (sourceMap === true && result.map && result.map.toString) {