fix empty resolver

app/src/app/order/[pk]/page.tsx

@@ -17,8 +17,11 @@ import {
   DESCRO_PROGRAM_ADDRESS,
   findResolverEntryPda,
 } from '@descro/sdk'
+import { isSome } from '@solana/kit'
 import type { Address } from '@solisting/sdk'
 
+const SYSTEM_PROGRAM = '11111111111111111111111111111111' as Address
+
 export default function OrderPage({ params }: { params: Promise<{ pk: string }> }) {
   const { pk } = use(params)
   const { account } = useWallet()
@@ -31,10 +34,14 @@ export default function OrderPage({ params }: { params: Promise<{ pk: string }>
   async function handleAccept() {
     if (!signer || !data) return
     const od = data.order.data
-    const [resolverEntry] = await findResolverEntryPda({ authority: od.resolver })
+    const resolverAddr = isSome(od.resolver) ? od.resolver.value : null
+    const resolverKey = resolverAddr ?? SYSTEM_PROGRAM
+    const [resolverEntry] = resolverAddr
+      ? await findResolverEntryPda({ authority: resolverAddr })
+      : [SYSTEM_PROGRAM]
     const ix = getAcceptOrderInstruction({
       seller: signer,
-      resolver: od.resolver,
+      resolver: resolverKey,
       listingAccount: od.listing,
       orderAccount: pk as Address,
       escrowAccount: od.escrowAccount,