values smaller than 0.001 sat/B can't be represented by CFeeRate, but they are not rejected.

```
./src/bitcoin-cli -named sendtoaddress address=bcrt1qwkmhqum095zau5rf2velq55cq938vrd7uw8m4r amount=1.23 fee_rate=0.0009

error code: -6
error message:
Fee rate (0.000 sat/vB) is lower than the minimum fee rate setting (1.000 sat/vB)
```

```
./src/bitcoin-cli -named sendtoaddress address=bcrt1qwkmhqum095zau5rf2velq55cq938vrd7uw8m4r amount=1.23 fee_rate=0.000000000009

error code: -3
error message:
Invalid amount

{RPCResult::Type::OBJ, "decoded", "Optional, the decoded transaction (only present when `verbose` is passed)",
                        {
                            {RPCResult::Type::ELISION, "", "Equivalent to the RPC decoderawtransaction method, or the RPC getrawtransaction method when `verbose` is passed."},
                        }},
                    })
                },
                RPCExamples{
                    HelpExampleCli("gettransaction", "\"1075db55d416d3ca199f55b6084e2115b9345e16c5cf302fc80e9d5fbf5d48d\"")
            + HelpExampleCli("gettransaction", "\"1075db55d416d3ca199f55b6084e2115b9345e16c5cf302fc80e9d5fbf5d48d\" true")
            + HelpExampleCli("gettransaction", "\"1075db55d416d3ca199f55b6084e2115b9345e16c5cf302fc80e9d5fbf5d48d\" false true")
            + HelpExampleRpc("gettransaction", "\"1075db55d416d3ca199f55b6084e2115b9345e16c5cf302fc80e9d5fbf5d48d\"")
                },
        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
{
    std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
    if (!pwallet) return NullUniValue;
    
    
    pwallet->BlockUntilSyncedToCurrentChain();
    LOCK(pwallet->cs_wallet);
    uint256 hash(ParseHashV(request.params[0], "txid"));
    isminefilter filter = ISMINE_SPENDABLE;
    if (ParseIncludeWatchonly(request.params[1], *pwallet)) {
        filter |= ISMINE_WATCH_ONLY;
    }
    bool verbose = request.params[2].isNull() ? false : request.params[2].get_bool();
    UniValue entry(UniValue::VOBJ);
    auto it = pwallet->mapWallet.find(hash);
    if (it == pwallet->mapWallet.end()) {
        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid or non-wallet transaction id");