fix: 渐变设置面板在切换操作对象后报错

src/views/Editor/Toolbar/ElementStylePanel/ShapeStylePanel.vue

@@ -196,7 +196,10 @@ const updateFillType = (type: 'gradient' | 'fill') => {
     slidesStore.removeElementProps({ id: handleElementId.value, propName: 'gradient' })
     addHistorySnapshot()
   }
-  else updateElement({ gradient: gradient.value })
+  else {
+    currentGradientIndex.value = 0
+    updateElement({ gradient: gradient.value })
+  }
 }
 
 // 设置渐变填充

src/views/Editor/Toolbar/SlideDesignPanel.vue

@@ -388,6 +388,7 @@ const updateBackgroundType = (type: SlideBackgroundType) => {
         rotate: 0,
       },
     }
+    currentGradientIndex.value = 0
     slidesStore.updateSlide({ background: newBackground })
   }
   addHistorySnapshot()