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

{
    return RPCHelpMan{"walletpassphrasechange",
                "\nChanges the wallet passphrase from 'oldpassphrase' to 'newpassphrase'.\n",
                {
                    {"oldpassphrase", RPCArg::Type::STR, RPCArg::Optional::NO, "The current passphrase"},
                    {"newpassphrase", RPCArg::Type::STR, RPCArg::Optional::NO, "The new passphrase"},
                },
                RPCResult{RPCResult::Type::NONE, "", ""},
                RPCExamples{