Fix Sentry JETPACK-ANDROID-1G9S and 1J82: avoid openUrl with empty url

ReaderActivityLauncher.openUrl() guards null/empty urls by reporting to
Sentry and returning, so these two issues are handled reports rather than
crashes. The root cause is two call sites passing empty urls, which also
left the user with a button that silently does nothing.

CommentDetailFragment only checked getAuthorUrl() != null, so an empty
author url still wired up a dead click listener. WPWebViewActivity's
"open in external browser" used mWebView.getUrl(), which is null until
the first page load finishes; it now falls back to the URL_TO_LOAD extra.

Fixes JETPACK-ANDROID-1G9S
Fixes JETPACK-ANDROID-1J82

Author: nbradbury

WordPress/src/main/java/org/wordpress/android/ui/WPWebViewActivity.java

@@ -348,8 +348,17 @@ private void initViewModel(WPWebViewUsageCategory webViewUsageCategory) {
         });
 
         mViewModel.getOpenExternalBrowser().observe(this, unit -> {
-            ReaderActivityLauncher.openUrl(WPWebViewActivity.this, mWebView.getUrl(),
-                    ReaderActivityLauncher.OpenUrlType.EXTERNAL);
+            // Prefer the currently loaded URL, but fall back to the requested URL when the page
+            // hasn't finished loading yet (mWebView.getUrl() is null before the first load).
+            String urlToOpen = mWebView.getUrl();
+            if (TextUtils.isEmpty(urlToOpen)) {
+                Bundle extras = getIntent().getExtras();
+                urlToOpen = extras != null ? extras.getString(URL_TO_LOAD) : null;
+            }
+            if (!TextUtils.isEmpty(urlToOpen)) {
+                ReaderActivityLauncher.openUrl(WPWebViewActivity.this, urlToOpen,
+                        ReaderActivityLauncher.OpenUrlType.EXTERNAL);
+            }
         });
 
         mViewModel.getPreviewModeSelector().observe(this, previewModelSelectorStatus -> {

WordPress/src/main/java/org/wordpress/android/ui/comments/CommentDetailFragment.java

@@ -831,7 +831,7 @@ private void showCommentWhenNonNull(
         updateStatusViews(binding, actionBinding, site, comment, note);
 
         // navigate to author's blog when avatar or name clicked
-        if (comment.getAuthorUrl() != null) {
+        if (!TextUtils.isEmpty(comment.getAuthorUrl())) {
             View.OnClickListener authorListener =
                     v -> ReaderActivityLauncher.openUrl(getActivity(), comment.getAuthorUrl());
             binding.imageAvatar.setOnClickListener(authorListener);