fix rotation error

doc/CHANGES.md

@@ -5,6 +5,7 @@ Change log
 <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
 **Table of Contents**  *generated with [DocToc](http://doctoc.herokuapp.com/)*
 
+- [10.3.0-dev (TBD)](#1030-dev-tbd)
 - [10.3.0 (2024-06-26)](#1030-2024-06-26)
 - [10.2.1 (2024-06-23)](#1021-2024-06-23)
 - [10.2.0 (2024-06-02)](#1020-2024-06-02)
@@ -112,6 +113,9 @@ Change log
 
 <!-- END doctoc generated TOC please keep comment here to allow auto update -->
 
+## 10.3.0-dev (TBD)
+* fix: [#2734](https://github.com/gridstack/gridstack.js/bug/2734) rotate() JS error
+
 ## 10.3.0 (2024-06-26)
 * fix: [#2720](https://github.com/gridstack/gridstack.js/pull/2720) load() now creates widgets in order (used to be reverse due to old collision code)
 

src/gridstack.ts

@@ -1447,7 +1447,10 @@ export class GridStack {
         rot.x = n.x + pivotX - (n.h - (pivotY+1));
         rot.y = (n.y + pivotY) - pivotX;
       }
+      Object.keys(rot).forEach(k => { if (rot[k] === undefined) delete rot[k]; });
+      const _orig = n._orig;
       this.update(el, rot);
+      n._orig = _orig; // restore as move() will delete it
     });
     return this;
   }

src/utils.ts

@@ -590,7 +590,10 @@ export class Utils {
   }
 
   /** swap the given object 2 field values */
-  public static swap(o: unknown, a: string, b: string): void { const tmp = o[a]; o[a] = o[b]; o[b] = tmp; }
+  public static swap(o: unknown, a: string, b: string): void {
+    if (!o) return;
+    const tmp = o[a]; o[a] = o[b]; o[b] = tmp;
+  }
 
   /** returns true if event is inside the given element rectangle */
   // Note: Safari Mac has null event.relatedTarget which causes #1684 so check if DragEvent is inside the coordinates instead