Update vnode.ts

Author: yyx990803

packages/runtime-core/src/vnode.ts

@@ -798,9 +798,9 @@ export function mergeProps(...args: (Data & VNodeProps)[]) {
         const existing = ret[key]
         const incoming = toMerge[key]
         if (
+          incoming &&
           existing !== incoming &&
-          !(isArray(existing) && existing.includes(incoming)) &&
-          incoming
+          !(isArray(existing) && existing.includes(incoming))
         ) {
           ret[key] = existing
             ? [].concat(existing as any, incoming as any)