feat: add stylelint prefix to CLI output (#279)

Author: ricardogobbosouza

src/StylelintError.js

@@ -3,7 +3,7 @@ class StylelintError extends Error {
    * @param {string=} messages
    */
   constructor(messages) {
-    super(messages);
+    super(`[stylelint] ${messages}`);
     this.name = 'StylelintError';
     this.stack = '';
   }

src/linter.js

@@ -67,7 +67,8 @@ export default function linter(key, options, compilation) {
     }
     rawResults.push(
       lintFiles(files).catch((e) => {
-        compilation.errors.push(e);
+        // @ts-ignore
+        compilation.errors.push(new StylelintError(e.message));
         return [];
       })
     );