fix: rspack doesn't have a watcher at first run

Author: felixmosh

lib/webpack/plugin.js

@@ -48,6 +48,11 @@ class I18NextHMRPlugin {
 
     compiler.hooks.watchRun.tap(pluginName, (compiler) => {
       const watcher = (compiler.watchFileSystem.wfs || compiler.watchFileSystem).watcher;
+
+      if (!watcher) {
+        return;
+      }
+
       const changedTimes = isWebpack5 ? watcher.getTimes() : watcher.mtimes;
 
       const { startTime = 0 } = watcher || {};