fix #1841

CHANGELOG.md

@@ -5,6 +5,7 @@
 - Added support for Android `WebViewFeature.isStartupFeatureSupported`, `WebViewFeature.STARTUP_FEATURE_SET_DIRECTORY_BASE_PATHS`, `WebViewFeature.STARTUP_FEATURE_SET_DATA_DIRECTORY_SUFFIX`, `WebViewFeature.WEB_MESSAGE_ARRAY_BUFFER`
 - Added `WebMessage.type` property
 - Fixed "iOS EXC_BAD_ACCESS crash on kill app with InAppWebView keyboard open" [#1837](https://github.com/pichillilorenzo/flutter_inappwebview/issues/1837)
+- Fixed "Flutter Web - TypeError: Failed to execute 'observe' on 'MutationObserver': parameter 1 is not of type 'Node'. error" [#1841](https://github.com/pichillilorenzo/flutter_inappwebview/issues/1841)
 
 ### BREAKING CHANGES
 

lib/assets/web/web_support.js

@@ -139,8 +139,10 @@ window.flutter_inappwebview = {
                             }
 
                             var initialTitle = iframe.contentDocument.title;
+                            var titleEl = iframe.contentDocument.querySelector('title');
                             webView.documentTitle = initialTitle;
                             window.flutter_inappwebview.nativeCommunication('onTitleChanged', viewId, [initialTitle]);
+                            if (titleEl != null) {
                                 new MutationObserver(function(mutations) {
                                     var title = mutations[0].target.innerText;
                                     if (title != webView.documentTitle) {
@@ -148,9 +150,10 @@ window.flutter_inappwebview = {
                                         window.flutter_inappwebview.nativeCommunication('onTitleChanged', viewId, [title]);
                                     }
                                 }).observe(
-                                iframe.contentDocument.querySelector('title'),
+                                    titleEl,
                                     { subtree: true, characterData: true, childList: true }
                                 );
+                            }
 
                             var oldPixelRatio = iframe.contentWindow.devicePixelRatio;
                             iframe.contentWindow.addEventListener('resize', function (e) {