Extract key from props in h() for UElement, keep key in props for URoot

src/core/h.ts

@@ -3,18 +3,19 @@ import type { UNode, UElement, URoot, UType, UComponent, UniversalProps } from "
 let _idCounter = 0;
 
 export function h(type: UType, props?: UniversalProps | null, ...children: UNode[]): UElement | URoot {
-  const { key, ...restProps } = props ?? {};
-  const resolvedProps: UniversalProps = restProps;
   const flatChildren = children.flat(Infinity as 1).filter((c: UNode) => c != null && c !== false) as UNode[];
 
   if (type === "root") {
     return {
       type: "root",
-      props: resolvedProps,
+      props: { ...(props ?? {}) },
       children: flatChildren,
     } as URoot;
   }
 
+  const { key, ...restProps } = props ?? {};
+  const resolvedProps: UniversalProps = restProps;
+
   return {
     type: type as string,
     props: resolvedProps,