Fix editor exit hang when GutenbergView never finishes loading (#22882)

Track ready state from `setEditorDidBecomeAvailable` and short-circuit
the save-on-exit flow to `UpdateFromEditor.Failed` when the editor
isn't ready. Bound the bridge latch with a 5s timeout that also routes
through `Failed`. Both paths skip mutating the `PostModel`, so the
user's existing draft is preserved when the editor stalls.

Fixes #22878

Author: jkmassel

RELEASE-NOTES.txt

@@ -2,7 +2,7 @@
 
 26.8
 -----
-
+* [**] Resolved an issue where the editor could become impossible to exit when it failed to load.
 
 26.7
 -----

WordPress/src/main/java/org/wordpress/android/ui/posts/GutenbergKitActivity.kt

@@ -1878,15 +1878,24 @@ class GutenbergKitActivity : BaseAppCompatActivity(), EditorImageSettingsListene
         updateAndSavePostAsync(listener, isFinishing)
     }
 
+    @Suppress("ReturnCount")
     private fun updateFromEditor(oldContent: String, isFinishing: Boolean = false): UpdateFromEditor {
         editorFragment?.let {
+            // Don't read title/content from a stalled editor — doing so would
+            // overwrite the in-memory PostModel with empty strings, and the
+            // postChanged observer would then persist that empty state to
+            // SQLite. See issue #22878.
+            if (!it.isEditorReady()) {
+                AppLog.w(AppLog.T.EDITOR, "Skipping content update: Gutenberg editor not ready")
+                return UpdateFromEditor.Failed(java.lang.Exception("Gutenberg editor not ready"))
+            }
             return try {
                 // To reduce redundant bridge events emitted to the Gutenberg editor, we get title and content at once
                 val titleAndContent = it.getTitleAndContent(oldContent, isFinishing)
                 val title = titleAndContent.first as String
                 val content = titleAndContent.second as String
                 PostFields(title, content)
-            } catch (e: EditorFragmentAbstract.EditorFragmentNotAddedException) {
+            } catch (e: GutenbergKitEditorFragmentBase.EditorFragmentNotAddedException) {
                 AppLog.e(AppLog.T.EDITOR, "Impossible to save the post, we weren't able to update it.")
                 UpdateFromEditor.Failed(e)
             }

WordPress/src/main/java/org/wordpress/android/ui/posts/editor/GutenbergKitEditorFragment.kt

@@ -42,6 +42,7 @@ import org.wordpress.gutenberg.GutenbergView.TitleAndContentCallback
 import org.wordpress.gutenberg.Media
 import org.wordpress.gutenberg.model.EditorConfiguration
 import java.util.concurrent.CountDownLatch
+import java.util.concurrent.TimeUnit
 import javax.inject.Inject
 
 class GutenbergKitEditorFragment : GutenbergKitEditorFragmentBase() {
@@ -51,6 +52,9 @@ class GutenbergKitEditorFragment : GutenbergKitEditorFragmentBase() {
     private var gutenbergView: GutenbergView? = null
     private var isHtmlModeEnabled = false
 
+    @Volatile
+    private var editorReady = false
+
     private val textWatcher = LiveTextWatcher()
     private var historyChangeListener: HistoryChangeListener? = null
     private var featuredImageChangeListener: FeaturedImageChangeListener? = null
@@ -257,7 +261,10 @@ class GutenbergKitEditorFragment : GutenbergKitEditorFragmentBase() {
             }
         )
 
+        editorReady = false
+
         gutenbergView.setEditorDidBecomeAvailable {
+            editorReady = true
             mEditorFragmentListener.onEditorFragmentContentReady(
                 ArrayList<Any?>(), false
             )
@@ -434,8 +441,19 @@ class GutenbergKitEditorFragment : GutenbergKitEditorFragmentBase() {
         )
 
         val finalResult = try {
-            latch.await()
-            result[0]
+            val completed = latch.await(
+                GET_TITLE_AND_CONTENT_TIMEOUT_SECONDS, TimeUnit.SECONDS
+            )
+            if (!completed) {
+                AppLog.w(
+                    AppLog.T.EDITOR,
+                    "Timed out waiting for title and content from " +
+                        "Gutenberg editor"
+                )
+                null
+            } else {
+                result[0]
+            }
         } catch (e: InterruptedException) {
             AppLog.w(
                 AppLog.T.EDITOR,
@@ -446,7 +464,10 @@ class GutenbergKitEditorFragment : GutenbergKitEditorFragmentBase() {
             null
         }
 
-        return finalResult ?: Pair("", "")
+        // Surface failure to the caller as a checked exception so it can
+        // skip mutating the PostModel rather than persisting empty content
+        // over the user's existing draft. See issue #22878.
+        return finalResult ?: throw EditorFragmentNotAddedException()
     }
 
     override fun getEditorName(): String {
@@ -517,6 +538,8 @@ class GutenbergKitEditorFragment : GutenbergKitEditorFragmentBase() {
         super.onDestroy()
     }
 
+    fun isEditorReady(): Boolean = editorReady
+
     fun setXPostsEnabled(enabled: Boolean) {
         isXPostsEnabled = enabled
     }
@@ -551,6 +574,8 @@ class GutenbergKitEditorFragment : GutenbergKitEditorFragmentBase() {
         private const val CAPTURE_PHOTO_PERMISSION_REQUEST_CODE = 101
         private const val CAPTURE_VIDEO_PERMISSION_REQUEST_CODE = 102
 
+        private const val GET_TITLE_AND_CONTENT_TIMEOUT_SECONDS = 5L
+
         fun newInstance(
             configuration: EditorConfiguration,
             site: SiteModel