fix: sets rpc result to null on rejection for EthereumProvider examples

dapps/react-dapp-v2-with-ethers/src/App.tsx

@@ -218,6 +218,7 @@ export default function App() {
         setRpcResult(result);
       } catch (error) {
         console.error("RPC request failed:", error);
+        setRpcResult(null);
       } finally {
         setIsRpcRequestPending(false);
       }

dapps/react-dapp-v2-with-web3js/src/App.tsx

@@ -227,6 +227,7 @@ export default function App() {
         setRpcResult(result);
       } catch (error) {
         console.error("RPC request failed:", error);
+        setRpcResult(null);
       } finally {
         setIsRpcRequestPending(false);
       }