Forward port Album cache delete/DESTROY issue with non-existant

keys in the cache.

docs/changelog/7.x.x.txt

@@ -22,6 +22,7 @@
  - fixed #9348: Required Upgrade Step Not Documented - 7.6.0
  - fixed #8993: Gallery Image Details Overlap Image
  - fixed #9380: CoolMenus template - invalid markup affecting page layouts
+ - fixed #9387: Asset Manager breaks navigating into a Gallery Album
 
 7.6.7
  - fixed #9263: Thingy possibleValues processing, and List type autodetection.

lib/WebGUI/Asset/Wobject/GalleryAlbum.pm

@@ -346,7 +346,7 @@ sub DESTROY {
     my $self        = shift;
     for my $key ( qw/ _nextAlbum _prevAlbum / ) {
         my $asset       = delete $self->{ $key };
-        $asset->DESTROY;
+        $asset->DESTROY if $asset;
     }
 }