From f8f5639b38f63402cc3b4a205c3d859b86c06fd4 Mon Sep 17 00:00:00 2001
From: Maksymilian Pawlak <120831+m4ksio@users.noreply.github.com>
Date: Thu, 28 Dec 2017 09:12:06 +0000
Subject: [PATCH] More descriptive error message (#2295)

---
 .../src/main/kotlin/net/corda/traderdemo/flow/SellerFlow.kt    | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/samples/trader-demo/src/main/kotlin/net/corda/traderdemo/flow/SellerFlow.kt b/samples/trader-demo/src/main/kotlin/net/corda/traderdemo/flow/SellerFlow.kt
index 2a08170192..3e91639000 100644
--- a/samples/trader-demo/src/main/kotlin/net/corda/traderdemo/flow/SellerFlow.kt
+++ b/samples/trader-demo/src/main/kotlin/net/corda/traderdemo/flow/SellerFlow.kt
@@ -40,7 +40,8 @@ class SellerFlow(private val otherParty: Party,
         progressTracker.currentStep = SELF_ISSUING
 
         val cpOwner = serviceHub.keyManagementService.freshKeyAndCert(ourIdentityAndCert, false)
-        val commercialPaper = serviceHub.vaultService.queryBy(CommercialPaper.State::class.java).states.first()
+        val commercialPaper = serviceHub.vaultService.queryBy(CommercialPaper.State::class.java)
+                .states.firstOrNull() ?: throw IllegalStateException("No commercial paper found. Please check if you issued the papers first, follow the README for instructions.")
 
         progressTracker.currentStep = TRADING