npm and error messages

node_modules/laravel-mix/src/webpackPlugins/BuildCallbackPlugin.js

@@ -0,0 +1,21 @@
+class BuildCallbackPlugin {
+    /**
+     * Create a new plugin instance.
+     *
+     * @param {Function} callback
+     */
+    constructor(callback) {
+        this.callback = callback;
+    }
+
+    /**
+     * Apply the plugin.
+     *
+     * @param {Object} compiler
+     */
+    apply(compiler) {
+        compiler.plugin('done', this.callback);
+    }
+}
+
+module.exports = BuildCallbackPlugin;