chore: improve code

Author: edison1105

packages/compiler-core/src/transforms/vSlot.ts

@@ -209,6 +209,7 @@ export function buildSlots(
 
     vFor = findDir(slotElement, 'for')
     if (vFor) vForProps = vFor.exp
+    else vForProps = undefined
     const slotFunction = buildSlotFn(slotProps, vForProps, slotChildren, slotLoc)
 
     // check if this slot is conditional (v-if/v-for)