add contract listner exception

Helius

2022-07-22 823aabb391a0cbd2eddf7c58c03b76e71967b964

 src/main/java/cc/mrbird/febs/dapp/chain/TrxService.java

@@ -113,4 +113,9 @@
    public BigInteger totalSupply() {
        return null;
    }

    @Override
    public String safeMintNFT(String toAddress) {
        return null;
    }
}