fix(api): normalize empty list responses

lib/api/disputes.ts

@@ -24,7 +24,7 @@ export type ListDisputesOptions = {
 }
 
 type Paginated<T> = {
-  items: T[]
+  items: T[] | null
   meta?: {
     total: number
     offset: number
@@ -50,6 +50,7 @@ function unwrapItems<T>(value: unknown): T[] {
   if ("items" in value) {
     const envelope = value as { items?: unknown }
     if (Array.isArray(envelope.items)) return envelope.items as T[]
+    if (envelope.items === null) return []
   }
   throw new Error("Invalid response")
 }