Fix extension loading

src/MainWindow.cpp

@@ -1181,6 +1181,9 @@ void MainWindow::loadExtension()
 
 void MainWindow::loadExtensionsFromSettings()
 {
+    if(!db.isOpen())
+        return;
+
     QStringList list = PreferencesDialog::getSettingsValue("extensions", "list").toStringList();
     foreach(QString ext, list)
     {

src/sqlitedb.cpp

@@ -1015,6 +1015,9 @@ bool DBBrowserDB::setPragma(const QString& pragma, int value, int& originalvalue
 
 bool DBBrowserDB::loadExtension(const QString& filename)
 {
+    if(!isOpen())
+        return false;
+
     // Check if file exists
     if(!QFile::exists(filename))
     {