Foundry v13 migraton, WIP

module/item-sheet.js

@@ -18,7 +18,7 @@ import { ItemAction } from "./item/item-actions.js";
 /**
  * Extend the basic ItemSheet for RdD specific items
  */
-export class RdDItemSheetV1 extends ItemSheet {
+export class RdDItemSheetV1 extends foundry.appv1.sheets.ItemSheet {
 
   static get ITEM_TYPE() {
     return undefined
@@ -31,7 +31,7 @@ export class RdDItemSheetV1 extends ItemSheet {
   }
 
   static register(sheetClass) {
-    Items.registerSheet(SYSTEM_RDD, sheetClass, {
+    foundry.documents.collections.Items.registerSheet(SYSTEM_RDD, sheetClass, {
       label: Misc.typeName('Item', sheetClass.ITEM_TYPE),
       types: [sheetClass.ITEM_TYPE],
       makeDefault: true