error: WalletInsufficientBalance error code added

src/error.rs

@@ -235,6 +235,9 @@ pub enum Error {
 
     #[error("Merkle tree already exists in wallet")]
     WalletTreeExists,
+    
+    #[error("Wallet insufficient balance")]
+    WalletInsufficientBalance,
 
     // ===================
     // wasm runtime errors