Resolve "Fix move slides on backend"

Closes #161 (closed)

client/src/pages/presentationEditor/PresentationEditorPage.tsx

@@ -122,7 +122,7 @@ const PresentationEditorPage: React.FC = () => {
       return
     }
     const draggedIndex = result.source.index
-    const draggedSlideId = sortedSlides.find((slide) => slide.order === draggedIndex)?.id
+    const draggedSlideId = sortedSlides[draggedIndex].id
     const slidesCopy = [...sortedSlides]
     const [removed] = slidesCopy.splice(draggedIndex, 1)
     slidesCopy.splice(result.destination.index, 0, removed)