Fix file deletion

CHDataManagement/Model/Item/LinkPreviewItem.swift

@@ -1,9 +1,18 @@
 
-protocol LinkPreviewItem {
+protocol LinkPreviewItem: AnyObject {
 
-    var linkPreviewImage: FileResource? { get }
+    var linkPreviewImage: FileResource? { get set }
 
     var linkPreviewTitle: String? { get }
 
     var linkPreviewDescription: String? { get }
 }
+
+extension LinkPreviewItem {
+
+    func remove(linkPreviewImage file: FileResource) {
+        if linkPreviewImage == file {
+            linkPreviewImage = nil
+        }
+    }
+}