[Refactor] Move shape fallback from LGraphCanvas to LGraphNode (#451)

* [Refactor] Move shape fallback from LGraphCanvas to LGraphNode

* nit

src/LGraphCanvas.ts

@@ -5175,7 +5175,7 @@ export class LGraphCanvas {
     const low_quality = this.low_quality
 
     const { collapsed } = node.flags
-    const shape = node._shape || node.constructor.shape || LiteGraph.NODE_DEFAULT_SHAPE
+    const shape = node.renderingShape
     const title_mode = node.title_mode
 
     const render_title = title_mode == TitleMode.TRANSPARENT_TITLE || title_mode == TitleMode.NO_TITLE

src/LGraphNode.ts

@@ -323,6 +323,13 @@ export class LGraphNode implements Positionable, IPinnable {
     }
   }
 
+  /**
+   * The shape of the node used for rendering. @see {@link RenderShape}
+   */
+  get renderingShape(): RenderShape {
+    return this._shape || this.constructor.shape || LiteGraph.NODE_DEFAULT_SHAPE
+  }
+
   public get is_selected(): boolean {
     return this.selected
   }