While some protocols require value attached to OP_RETURN outputs, this otherwise seems like a mistake.

Setting the value to 0 should really be done by the wallet/script creating the transaction (like createrawtransaction does for `data` outputs). However, as an additional check, similar to the high-fee check, sendrawtransaction could also check for non-zero value OP_RETURN outputs.

This should be configurable by a new RPC argument.

See also https://transactionfee.info/charts/output-opreturn-amount/

#### Useful skills:

* Bitcoin Core RPC code
* Transaction output types
* Bitcoin Core functional tests

#### Want to work on this issue?

For guidance on contributing, please read [CONTRIBUTING.md](https://github.com/bitcoin/bitcoin/blob/master/CONTRIBUTING.md) before opening your pull request.

+ HelpExampleRpc("gettxspendingprevout", "\"[{\\\"txid\\\":\\\"a08e6907dbbd3d809776dbfc5d82e371b764ed838b5655e72f463568df1aadf0\\\",\\\"vout\\\":3}]\"")
        },
        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
        {
            const UniValue& output_params = request.params[0].get_array();
            if (output_params.empty()) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, outputs are missing");
            }
            std::vector<COutPoint> prevouts;
            prevouts.reserve(output_params.size());
            for (unsigned int idx = 0; idx < output_params.size(); idx++) {
                const UniValue& o = output_params[idx].get_obj();
                RPCTypeCheckObj(o,
                                {
                                    {"txid", UniValueType(UniValue::VSTR)},
                                    {"vout", UniValueType(UniValue::VNUM)},
                                }, false, true);
                const uint256 txid(ParseHashO(o, "txid"));
                const int nOutput{find_value(o, "vout").getInt<int>()};
                if (nOutput < 0) {
                    throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, vout cannot be negative");
                }
                prevouts.emplace_back(txid, nOutput);
            }
            const CTxMemPool& mempool = EnsureAnyMemPool(request.context);
            LOCK(mempool.cs);
            UniValue result{UniValue::VARR};
            for (const COutPoint& prevout : prevouts) {
                UniValue o(UniValue::VOBJ);
                o.pushKV("txid", prevout.hash.ToString());