From 6e5f3c5aa90be013c90f34af8c6508f1e26d87a7 Mon Sep 17 00:00:00 2001
From: Oliver Kopp <kopp.dev@gmail.com>
Date: Tue, 30 Jan 2024 17:07:01 +0100
Subject: [PATCH] Fix NPE when tab is close during load (#10841)

---
 src/main/java/org/jabref/gui/LibraryTab.java  | 39 +++++++++++++++----
 .../org/jabref/gui/util/BackgroundTask.java   |  5 +++
 2 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/src/main/java/org/jabref/gui/LibraryTab.java b/src/main/java/org/jabref/gui/LibraryTab.java
index 31c3c4bfc07..ea00153a7a4 100644
--- a/src/main/java/org/jabref/gui/LibraryTab.java
+++ b/src/main/java/org/jabref/gui/LibraryTab.java
@@ -25,6 +25,7 @@
 import javafx.scene.control.ProgressIndicator;
 import javafx.scene.control.SplitPane;
 import javafx.scene.control.Tab;
+import javafx.scene.control.TabPane;
 import javafx.scene.control.Tooltip;
 import javafx.scene.layout.BorderPane;
 import javafx.util.Duration;
@@ -261,7 +262,12 @@ private void onDatabaseLoadingFailed(Exception ex) {
     }
 
     private void setDatabaseContext(BibDatabaseContext bibDatabaseContext) {
-        if (this.getTabPane().getSelectionModel().selectedItemProperty().get().equals(this)) {
+        TabPane tabPane = this.getTabPane();
+        if (tabPane == null) {
+            LOGGER.debug("User interrupted loading. Not showing any library.");
+            return;
+        }
+        if (tabPane.getSelectionModel().selectedItemProperty().get().equals(this)) {
             LOGGER.debug("This case should not happen.");
             stateManager.setActiveDatabase(bibDatabaseContext);
         }
@@ -778,12 +784,31 @@ private void onCloseRequest(Event event) {
      * Perform necessary cleanup when this Library is closed.
      */
     private void onClosed(Event event) {
-        changeMonitor.ifPresent(DatabaseChangeMonitor::unregister);
-        PdfIndexerManager.shutdownIndexer(bibDatabaseContext);
-        AutosaveManager.shutdown(bibDatabaseContext);
-        BackupManager.shutdown(bibDatabaseContext,
-                preferencesService.getFilePreferences().getBackupDirectory(),
-                preferencesService.getFilePreferences().shouldCreateBackup());
+        if (dataLoadingTask != null) {
+            dataLoadingTask.cancel();
+        }
+        try {
+            changeMonitor.ifPresent(DatabaseChangeMonitor::unregister);
+        } catch (RuntimeException e) {
+            LOGGER.error("Problem when closing change monitor", e);
+        }
+        try {
+            PdfIndexerManager.shutdownIndexer(bibDatabaseContext);
+        } catch (RuntimeException e) {
+            LOGGER.error("Problem when shutting down PDF indexer", e);
+        }
+        try {
+            AutosaveManager.shutdown(bibDatabaseContext);
+        } catch (RuntimeException e) {
+            LOGGER.error("Problem when shutting down autosave manager", e);
+        }
+        try {
+            BackupManager.shutdown(bibDatabaseContext,
+                    preferencesService.getFilePreferences().getBackupDirectory(),
+                    preferencesService.getFilePreferences().shouldCreateBackup());
+        } catch (RuntimeException e) {
+            LOGGER.error("Problem when shutting down backup manager", e);
+        }
     }
 
     /**
diff --git a/src/main/java/org/jabref/gui/util/BackgroundTask.java b/src/main/java/org/jabref/gui/util/BackgroundTask.java
index 9e6fe46980c..a0eda270279 100644
--- a/src/main/java/org/jabref/gui/util/BackgroundTask.java
+++ b/src/main/java/org/jabref/gui/util/BackgroundTask.java
@@ -22,6 +22,8 @@
 
 import com.google.common.collect.ImmutableMap;
 import com.tobiasdiez.easybind.EasyBind;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * This class is essentially a wrapper around {@link Task}.
@@ -37,6 +39,8 @@ public abstract class BackgroundTask<V> {
             Localization.lang("Downloading"), IconTheme.JabRefIcons.DOWNLOAD.getGraphicNode()
     );
 
+    private static final Logger LOGGER = LoggerFactory.getLogger(BackgroundTask.class);
+
     private Runnable onRunning;
     private Consumer<V> onSuccess;
     private Consumer<Exception> onException;
@@ -92,6 +96,7 @@ public boolean isCanceled() {
     }
 
     public void cancel() {
+        LOGGER.debug("Canceling task");
         this.isCanceled.set(true);
     }