minor: improve eth/poly fees error message

cw_evm/lib/evm_chain_exceptions.dart

@@ -16,8 +16,8 @@ class EVMChainTransactionCreationException implements Exception {
 class EVMChainTransactionFeesException implements Exception {
   final String exceptionMessage;
 
-  EVMChainTransactionFeesException()
-      : exceptionMessage = 'Current balance is less than the estimated fees for this transaction.';
+  EVMChainTransactionFeesException(String currency)
+      : exceptionMessage = 'Transaction failed due to insufficient $currency balance to cover the fees.';
 
   @override
   String toString() => exceptionMessage;

cw_evm/lib/evm_chain_wallet.dart

@@ -417,7 +417,7 @@ abstract class EVMChainWalletBase
 
       // check the fees on the base currency (Eth/Polygon)
       if (estimatedFeesForTransaction > balance[currency]!.balance) {
-        throw EVMChainTransactionFeesException();
+        throw EVMChainTransactionFeesException(currency.title);
       }
 
       if (currencyBalance.balance < totalAmount) {