From e754fad581f1d8948ed9ce9b4a4f6a25252b1d53 Mon Sep 17 00:00:00 2001
From: Simon Warta <simon@warta.it>
Date: Thu, 28 Oct 2021 16:29:41 +0200
Subject: [PATCH] Fix response error handling for smart queries

---
 CHANGELOG.md                                   |  4 ++++
 packages/cosmwasm-stargate/src/queries/wasm.ts | 10 ++++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 72d7a936..f9f4891b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,10 @@ and this project adheres to
 
 ## [Unreleased]
 
+### Fixed
+
+- @cosmjs/cosmwasm-stargate: Fix response error handling for smart queries.
+
 ## [0.26.3] - 2021-10-25
 
 ### Added
diff --git a/packages/cosmwasm-stargate/src/queries/wasm.ts b/packages/cosmwasm-stargate/src/queries/wasm.ts
index 8cd7c521..1f851f70 100644
--- a/packages/cosmwasm-stargate/src/queries/wasm.ts
+++ b/packages/cosmwasm-stargate/src/queries/wasm.ts
@@ -120,10 +120,16 @@ export function setupWasmExtension(base: QueryClient): WasmExtension {
         const request = { address: address, queryData: toAscii(JSON.stringify(query)) };
         const { data } = await queryService.SmartContractState(request);
         // By convention, smart queries must return a valid JSON document (see https://github.com/CosmWasm/cosmwasm/issues/144)
+        let responseText: string;
         try {
-          return JSON.parse(fromUtf8(data));
+          responseText = fromUtf8(data);
         } catch (error) {
-          throw new Error("Contract did not return valid JSON data");
+          throw new Error(`Could not UTF-8 decode smart query response from contract: ${error}`);
+        }
+        try {
+          return JSON.parse(responseText);
+        } catch (error) {
+          throw new Error(`Could not JSON parse smart query response from contract: ${error}`);
         }
       },
     },