fix crash issues

src/widgets/dialogs/importfolderdialog.cpp

@@ -84,6 +84,15 @@ bool ImportFolderDialog::importFolder()
 {
     const auto folder = m_filterWidget->getFolderPath();
     auto nb = m_parentNode->getNotebook();
+    if (PathUtils::pathContains(folder, m_parentNode->fetchAbsolutePath()))
+    {
+        // Avoid recursive import.
+        auto msg = tr("Failed to add folder (%1) as node under (%2).").arg(folder, m_parentNode->fetchAbsolutePath());
+        qCritical() << msg;
+        setInformationText(msg, ScrollDialog::InformationLevel::Error);
+        return false;
+    }
+
     m_newNode = nullptr;
     try {
         m_newNode = nb->copyAsNode(m_parentNode, Node::Flag::Container, folder);

src/widgets/dialogs/managenotebooksdialog.cpp

@@ -163,8 +163,12 @@ void ManageNotebooksDialog::loadNotebooks(const Notebook *p_notebook)
         }
     }
 
-    if (!hasCurrentItem && !notebooks.isEmpty()) {
-        m_notebookList->setCurrentRow(0);
+    if (!hasCurrentItem) {
+        if (notebooks.isEmpty()) {
+            selectNotebook(nullptr);
+        } else {
+            m_notebookList->setCurrentRow(0);
+        }
     }
 }
 
@@ -173,6 +177,10 @@ void ManageNotebooksDialog::selectNotebook(Notebook *p_notebook)
     m_notebookInfoWidget->setNotebook(p_notebook);
     setChangesUnsaved(false);
 
+    // Update buttons.
+    m_closeNotebookBtn->setEnabled(p_notebook);
+    m_deleteNotebookBtn->setEnabled(p_notebook);
+
     WidgetUtils::resizeToHideScrollBarLater(m_infoScrollArea, false, true);
 }
 
@@ -217,7 +225,10 @@ bool ManageNotebooksDialog::saveChangesToNotebook()
 
 void ManageNotebooksDialog::closeNotebook(const Notebook *p_notebook)
 {
-    Q_ASSERT(p_notebook);
+    if (!p_notebook) {
+        return;
+    }
+
     int ret = MessageBoxHelper::questionOkCancel(MessageBoxHelper::Question,
                                                  tr("Close notebook (%1)?")
                                                    .arg(p_notebook->getName()),
@@ -244,7 +255,10 @@ void ManageNotebooksDialog::closeNotebook(const Notebook *p_notebook)
 
 void ManageNotebooksDialog::removeNotebook(const Notebook *p_notebook)
 {
-    Q_ASSERT(p_notebook);
+    if (!p_notebook) {
+        return;
+    }
+
     int ret = MessageBoxHelper::questionOkCancel(MessageBoxHelper::Warning,
                                                  tr("Delete notebook (%1) from disk?").arg(p_notebook->getName()),
                                                  tr("CALM DOWN! CALM DOWN! CALM DOWN! It will delete all files belonging to this notebook from disk. "