fix: don't break loader on invalid or not exists url or import token (#827)

Author: evilebottnawi

lib/loader.js

@@ -130,7 +130,12 @@ module.exports = function loader(content, map) {
       // Prepare replacer to change from `___CSS_LOADER_IMPORT___INDEX___` to `require('./file.css').locals`
       const importItemReplacer = (item) => {
         const match = placholderRegExps.importItem.exec(item);
-        const idx = +match[1];
+        const idx = Number(match[1]);
+
+        if (!importItems[idx]) {
+          return item;
+        }
+
         const importItem = importItems[idx];
         const importUrl = importUrlPrefix + importItem.url;
 
@@ -208,7 +213,12 @@ module.exports = function loader(content, map) {
           placholderRegExps.urlItemG,
           (item) => {
             const match = placholderRegExps.urlItem.exec(item);
-            let idx = +match[1];
+            let idx = Number(match[1]);
+
+            if (!urlItems[idx]) {
+              return item;
+            }
+
             const urlItem = urlItems[idx];
             const { url } = urlItem;