fix: add shutter api check

Author: kemuru

web/src/pages/Cases/CaseDetails/Voting/Shutter/Commit.tsx

@@ -85,6 +85,10 @@ const Commit: React.FC<ICommit> = ({
 
   const handleCommit = useCallback(
     async (choice: bigint) => {
+      if (!import.meta.env.REACT_APP_SHUTTER_API) {
+        console.error("REACT_APP_SHUTTER_API environment variable is not set");
+        throw new Error("Cannot commit vote: REACT_APP_SHUTTER_API environment variable is required but not set");
+      }
       const message = { message: saltKey };
       const rawSalt = !isUndefined(signingAccount)
         ? await signingAccount.signMessage(message)