check for $block.data, to verify that the blockObject is not in a destroyed state.

src/Umbraco.Web.UI.Client/src/views/propertyeditors/blocklist/umbBlockListPropertyEditor.component.js

@@ -135,7 +135,8 @@
 
             // Append the blockObjects to our layout.
             vm.layout.forEach(entry => {
-                if (entry.$block === undefined || entry.$block === null) {
+                // $block must have the data property to be a valid BlockObject, if not its concidered as a destroyed blockObject.
+                if (entry.$block === undefined || entry.$block === null || entry.$block.data === undefined) {
                     var block = getBlockObject(entry);
     
                     // If this entry was not supported by our property-editor it would return 'null'.