fixup: check account balance + faucet

vochain/state/account.go

@@ -103,6 +103,20 @@ func (v *State) GetAccount(address common.Address, committed bool) (*Account, er
 	return &acc, acc.Unmarshal(raw)
 }
 
+// GetAccountBalance retrieves the Account.Balance for an address.
+// Returns 0 and no error if the account does not exist.
+// Committed is relative to the state on which the function is executed.
+func (v *State) GetAccountBalance(address common.Address, committed bool) (uint64, error) {
+	acc, err := v.GetAccount(address, committed)
+	if err != nil {
+		return 0, err
+	}
+	if acc == nil {
+		return 0, nil
+	}
+	return acc.Balance, nil
+}
+
 // CountAccounts returns the overall number of accounts the vochain has
 func (v *State) CountAccounts(committed bool) (uint64, error) {
 	// TODO: Once statedb.TreeView.Size() works, replace this by that.

vochain/transaction/transaction.go

@@ -669,6 +669,17 @@ func (t *TransactionHandler) checkFaucetPackageAndTransfer(txFaucetPackage *mode
 		)
 	}
 
+	balance, err := t.state.GetAccountBalance(txSenderAddress, false)
+	if err != nil {
+		return false, fmt.Errorf("cannot get tx sender balance: %w", err)
+	}
+	if balance+faucetPayload.Amount < txCost {
+		return false, fmt.Errorf(
+			"account balance (%d) + faucet amount (%d) is not enough to pay the tx cost %d",
+			balance, faucetPayload.Amount, txCost,
+		)
+	}
+
 	// if forCommit, then the cost of the transaction is consumed from the faucet
 	if forCommit {
 		if err := t.state.ConsumeFaucetPayload(