Use better way to handle gallery with no images and page with no images

lib/components/gallery_basic_info.dart

@@ -10,7 +10,7 @@ class GalleryBasicInfo extends StatelessWidget {
   const GalleryBasicInfo(this.gMeta, this.firstPage,
       {super.key, this.fileId, this.gData, this.files});
   final GMeta gMeta;
-  final ExtendedPMeta firstPage;
+  final ExtendedPMeta? firstPage;
   final int? fileId;
   final GalleryData? gData;
   final EhFiles? files;
@@ -27,7 +27,9 @@ class GalleryBasicInfo extends StatelessWidget {
                 flex: 2,
                 child: Container(
                   margin: const EdgeInsets.only(right: 8),
-                  child: Thumbnail(firstPage, fileId: fileId, gid: gMeta.gid),
+                  child: firstPage != null
+                      ? Thumbnail(firstPage!, fileId: fileId, gid: gMeta.gid)
+                      : Container(),
                 )),
             Expanded(
                 flex: 3,

lib/components/gallery_info.dart

@@ -53,9 +53,9 @@ class _GalleryInfo extends State<GalleryInfo> with ThemeModeWidget {
   @override
   Widget build(BuildContext context) {
     bool useMobile = MediaQuery.of(context).size.width <= 810;
-    final firstPage = widget.gData.pages.first;
-    final int? firstFileId = widget.files != null
-        ? widget.files!.files[firstPage.token]!.first.id
+    final firstPage = widget.gData.pages.firstOrNull;
+    final int? firstFileId = widget.files != null && firstPage != null
+        ? widget.files!.files[firstPage!.token]!.firstOrNull?.id
         : null;
     return CustomScrollView(
       controller: controller,

lib/components/gallery_info_desktop.dart

@@ -59,9 +59,12 @@ class GalleryInfoDesktop extends StatelessWidget {
             child: Row(children: [
               Expanded(
                   flex: 3,
-                  child: Padding(padding: const EdgeInsets.only(right: 8.0),
-                    child: Thumbnail(gData.pages.first,
-                      fileId: fileId, gid: gData.meta.gid))),
+                  child: Padding(
+                      padding: const EdgeInsets.only(right: 8.0),
+                      child: gData.pages.isNotEmpty
+                          ? Thumbnail(gData.pages.first,
+                              fileId: fileId, gid: gData.meta.gid)
+                          : Container())),
               Expanded(
                   flex: 7,
                   child: Column(

lib/components/thumbnail_gridview.dart

@@ -23,7 +23,7 @@ class ThumbnailGridView extends StatelessWidget {
         itemBuilder: (context, index) {
           final page = npages[index]!;
           final fileId =
-              files != null ? files!.files[page.token]!.first.id : null;
+              files != null ? files!.files[page.token]!.firstOrNull?.id : null;
           final key = Key("thumbnail$gid-${page.index}");
           return Container(
               padding: const EdgeInsets.all(4),