Fix bug

lib/platform/replace_current_route.dart

@@ -0,0 +1 @@
+export 'replace_current_route_none.dart' if (dart.library.html) 'replace_current_route_web.dart';

lib/platform/replace_current_route_none.dart

@@ -0,0 +1,3 @@
+void replaceCurrentRoute(String query) {
+    throw UnimplementedError();
+}

lib/platform/replace_current_route_web.dart

@@ -0,0 +1,13 @@
+// ignore: avoid_web_libraries_in_flutter
+import 'dart:html';
+
+void replaceCurrentRoute(String query) {
+  const usePathUrl = bool.fromEnvironment("usePathUrl");
+  if (usePathUrl) {
+    final q = query.substring(1);
+    final base = document.baseUri ?? "/";
+    window.history.replaceState(null, "", "$base$q");
+  } else {
+    window.history.replaceState(null, "", "#$query");
+  }
+}

lib/viewer/single.dart

@@ -1,5 +1,6 @@
 import 'package:dio/dio.dart';
 import 'package:dio_image_provider/dio_image_provider.dart';
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/scheduler.dart';
 import 'package:flutter/services.dart';
@@ -12,6 +13,7 @@ import 'package:photo_view/photo_view_gallery.dart';
 import '../api/file.dart';
 import '../api/gallery.dart';
 import '../globals.dart';
+import '../platform/replace_current_route.dart';
 
 final _log = Logger("SinglePageViewer");
 
@@ -84,6 +86,7 @@ class _SinglePageViewer extends State<SinglePageViewer> with ThemeModeWidget {
         }
         setState(() {
           _files = fileData;
+          _error = null;
           _isLoading = false;
         });
       }
@@ -99,9 +102,15 @@ class _SinglePageViewer extends State<SinglePageViewer> with ThemeModeWidget {
   }
 
   void _onPageChanged(BuildContext context) {
-    context.replace("/gallery/${widget.gid}/page/${_index + 1}",
+    GoRouter.optionURLReflectsImperativeAPIs = false;
+    final q = "/gallery/${widget.gid}/page/${_index + 1}";
+    context.replace(q,
         extra: SinglePageViewerExtra(data: _data, files: _files));
+    GoRouter.optionURLReflectsImperativeAPIs = true;
     _page_changed = false;
+    if (kIsWeb) {
+      replaceCurrentRoute(q);
+    }
   }
 
   @override
@@ -152,7 +161,6 @@ class _SinglePageViewer extends State<SinglePageViewer> with ThemeModeWidget {
         bindings: [
           KeyAction(LogicalKeyboardKey.arrowLeft, "previous page", () {
             if (_index > 0) {
-              _index -= 1;
               _pageController.previousPage(
                   duration: const Duration(milliseconds: 200),
                   curve: Curves.easeInOut);
@@ -160,7 +168,6 @@ class _SinglePageViewer extends State<SinglePageViewer> with ThemeModeWidget {
           }),
           KeyAction(LogicalKeyboardKey.arrowRight, "next page", () {
             if (_index < _data!.pages.length - 1) {
-              _index += 1;
               _pageController.nextPage(
                   duration: const Duration(milliseconds: 200),
                   curve: Curves.easeInOut);