[mob][photos] Assert or log depending on the context if inherited widget holding selection state is used in a wrong way

mobile/lib/ui/viewer/actions/file_selection_overlay_bar.dart

@@ -117,6 +117,10 @@ class _SelectAllButtonState extends State<SelectAllButton> {
   @override
   Widget build(BuildContext context) {
     final selectionState = SelectionState.of(context);
+    assert(
+      selectionState != null,
+      "SelectionState not found in context, SelectionState should be an ancestor of FileSelectionOverlayBar",
+    );
     final colorScheme = getEnteColorScheme(context);
     return GestureDetector(
       onTap: () {
@@ -155,7 +159,7 @@ class _SelectAllButtonState extends State<SelectAllButton> {
               ),
               const SizedBox(width: 4),
               ListenableBuilder(
-                listenable: selectionState.selectedFiles,
+                listenable: selectionState!.selectedFiles,
                 builder: (context, _) {
                   if (selectionState.selectedFiles.files.length ==
                       selectionState.allGalleryFiles?.length) {

mobile/lib/ui/viewer/gallery/state/selection_state.dart

@@ -1,4 +1,5 @@
 import "package:flutter/material.dart";
+import "package:logging/logging.dart";
 import "package:photos/models/file/file.dart";
 import "package:photos/models/selected_files.dart";
 
@@ -22,10 +23,14 @@ class SelectionState extends InheritedWidget {
     return context.dependOnInheritedWidgetOfExactType<SelectionState>();
   }
 
-  static SelectionState of(BuildContext context) {
+  static SelectionState? of(BuildContext context) {
     final SelectionState? result = maybeOf(context);
-    assert(result != null, 'No SelectionState found in context');
-    return result!;
+    if (result == null) {
+      Logger("SelectionState").warning(
+        "No SelectionState found in context. Ignore this if file selection is disabled in the gallery used.",
+      );
+    }
+    return result;
   }
 
   @override