Fix file rename crash after toggling split mode.

editor/filesystem_dock.cpp

@@ -88,6 +88,7 @@ void FileSystemList::_line_editor_submit(String p_text) {
 bool FileSystemList::edit_selected() {
 	ERR_FAIL_COND_V_MSG(!is_anything_selected(), false, "No item selected.");
 	int s = get_current();
+	ERR_FAIL_COND_V_MSG(s < 0, false, "No current item selected.");
 	ensure_current_is_visible();
 
 	Rect2 rect;
@@ -907,12 +908,13 @@ void FileSystemDock::_sort_file_info_list(List<FileSystemDock::FileInfo> &r_file
 }
 
 void FileSystemDock::_update_file_list(bool p_keep_selection) {
-	// Register the previously selected items.
-	HashSet<String> cselection;
+	// Register the previously current and selected items.
+	HashSet<String> previous_selection;
+	HashSet<int> valid_selection;
 	if (p_keep_selection) {
 		for (int i = 0; i < files->get_item_count(); i++) {
 			if (files->is_selected(i)) {
-				cselection.insert(files->get_item_text(i));
+				previous_selection.insert(files->get_item_text(i));
 			}
 		}
 	}
@@ -1068,8 +1070,9 @@ void FileSystemDock::_update_file_list(bool p_keep_selection) {
 					Color this_folder_color = has_custom_color ? folder_colors[assigned_folder_colors[dpath]] : inherited_folder_color;
 					files->set_item_icon_modulate(-1, editor_is_dark_theme ? this_folder_color : this_folder_color * 1.75);
 
-					if (cselection.has(dname)) {
+					if (previous_selection.has(dname)) {
 						files->select(files->get_item_count() - 1, false);
+						valid_selection.insert(files->get_item_count() - 1);
 					}
 				}
 			}
@@ -1142,8 +1145,9 @@ void FileSystemDock::_update_file_list(bool p_keep_selection) {
 		}
 
 		// Select the items.
-		if (cselection.has(fname)) {
+		if (previous_selection.has(fname)) {
 			files->select(item_index, false);
+			valid_selection.insert(item_index);
 		}
 
 		if (!p_keep_selection && !file.is_empty() && fname == file) {
@@ -1159,6 +1163,11 @@ void FileSystemDock::_update_file_list(bool p_keep_selection) {
 		}
 		files->set_item_tooltip(item_index, tooltip);
 	}
+
+	// If we only have any selected items retained, we need to update the current idx.
+	if (!valid_selection.is_empty()) {
+		files->set_current(*valid_selection.begin());
+	}
 }
 
 void FileSystemDock::_select_file(const String &p_path, bool p_select_in_favorites) {