fix(datastore) fix crash caused by null patchItem (#1123)

Author: richardmcclellan

aws-datastore/src/main/java/com/amplifyframework/datastore/storage/sqlite/SQLiteStorageAdapter.java

@@ -578,6 +578,7 @@ public <T extends Model> void delete(
                     ModelSchema schema = modelSchemaRegistry.getModelSchemaForModelInstance(model);
                     itemChangeSubject.onNext(StorageItemChange.builder()
                             .item(model)
+                            .patchItem(SerializedModel.create(model, schema))
                             .modelSchema(schema)
                             .type(StorageItemChange.Type.DELETE)
                             .predicate(QueryPredicates.all())