fix: optional chaining bug

package.json

@@ -1,6 +1,6 @@
 {
   "name": "pdf-viewer-vue",
-  "version": "0.2.0",
+  "version": "0.2.1",
   "description": "PDF viewer component for Vue 2 and Vue 3",
   "keywords": [
     "vue",

src/components/Viewer/Viewer.vue

@@ -207,7 +207,7 @@ export default {
   methods: {
     printPDF() {
       const contentWindow = this.$refs.iframe.getContentWindow()
-      contentWindow?.print()
+      contentWindow.print()
     },
     updateZoomFullpage() {
       const perViewerHeight = this.viewerContentHeight / this.total