rpc: Reject empty txids in gettxoutproof

src/rpc/rawtransaction.cpp

@@ -245,6 +245,9 @@ static RPCHelpMan gettxoutproof()
 {
     std::set<uint256> setTxids;
     UniValue txids = request.params[0].get_array();
+    if (txids.empty()) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "Parameter 'txids' cannot be empty");
+    }
     for (unsigned int idx = 0; idx < txids.size(); idx++) {
         auto ret = setTxids.insert(ParseHashV(txids[idx], "txid"));
         if (!ret.second) {

test/functional/rpc_txoutproof.py

@@ -78,7 +78,7 @@ class MerkleBlockTest(BitcoinTestFramework):
         # We can't get a proof if we specify transactions from different blocks
         assert_raises_rpc_error(-5, "Not all transactions found in specified or retrieved block", self.nodes[0].gettxoutproof, [txid1, txid3])
         # Test empty list
-        assert_raises_rpc_error(-5, "Transaction not yet in block", self.nodes[0].gettxoutproof, [])
+        assert_raises_rpc_error(-8, "Parameter 'txids' cannot be empty", self.nodes[0].gettxoutproof, [])
         # Test duplicate txid
         assert_raises_rpc_error(-8, 'Invalid parameter, duplicated txid', self.nodes[0].gettxoutproof, [txid1, txid1])