While working on this PR https://github.com/bitcoin/bitcoin/pull/18570 I ran into a bit confusing situation where in one function a **CWallet reference** was expected while two others dealt with **CWallet pointers**. My initial reaction was: `let's harmonize them by making them references`. However, not being part of the PR itself I did't change anything and completed the PR first.

Now, after having analyzed the `rpcwallet.cpp` code I came to the conclusion that:

* converting them all into references is not the solution as they're originally **shared_ptr**s
* but also: there is no (visible) reason why every RPC function should begin like this:

```cpp
std::shared_ptr<CWallet> const pwallet = GetWalletForJSONRPCRequest(request);
const CWallet* const pwallet = wallet.get();
```

This clearly defeats the purpose of shared pointers for no obvious reason. *Maybe I am missing something?*

In my (unpublished) [code changes](https://github.com/brakmic/bitcoin/commit/0b3ee615491edf6f542631bf6ae6f72eac406550) all raw pointers got replaced with **shared_ptr**s but kept their original names (that is, *pwallet*). In the end, they're pointers too, so the most of the original code remained untouched.

However, some of the helper functions couldn't be changed because external code is accessing them and I didn't want to make this task "virulent". So I introduced new ("Ref") variants that expect **shared_ptr** parameters, namely: 

```cpp
void EnsureWalletRefIsUnlocked(const std::shared_ptr<CWallet>);
bool EnsureWalletRefIsAvailable(const std::shared_ptr<CWallet>, bool avoidException);
```

I have tested the code, with python and boost-tests, and could not find any errors. 
But before opening a PR I would like to open a discussion about this. 

Is there any reason to keep on working with raw pointers when every function call actually begins with *shared_ptr*s?

Regards,
{"fee_rate", RPCArg::Type::AMOUNT,  "not set, fall back to wallet fee estimation",
                             "\nSpecify a fee rate in " + CURRENCY_ATOM + "/vB instead of relying on the built-in fee estimator.\n"
                             "Must be at least " + incremental_fee + " higher than the current transaction fee rate.\n"
                             "WARNING: before version 0.21, fee_rate was in " + CURRENCY_UNIT + "/kvB. As of 0.21, fee_rate is in " + CURRENCY_ATOM + "/vB.\n"},
                    {"replaceable", RPCArg::Type::BOOL,  "true", "Whether the new transaction should still be\n"
                             "marked bip-125 replaceable. If true, the sequence numbers in the transaction will\n"
                             "be left unchanged from the original. If false, any input sequence numbers in the\n"
                             "original transaction that were less than 0xfffffffe will be increased to 0xfffffffe\n"
                             "so the new transaction will not be explicitly bip-125 replaceable (though it may\n"
                             "still be replaceable in practice, for example if it has unconfirmed ancestors which\n"
                             "are replaceable).\n"},
                    {"estimate_mode", RPCArg::Type::STR,  "unset", std::string() + "The fee estimate mode, must be one of (case insensitive):\n"
    "         \"" + FeeModes("\"\n\"") + "\""},
                },
                "options"},
        },
        RPCResult{
            RPCResult::Type::OBJ, "", "", Cat(Cat<std::vector<RPCResult>>(
            {
                {RPCResult::Type::STR, "psbt", "The base64-encoded unsigned PSBT of the new transaction." + std::string(want_psbt ? "" : " Only returned when wallet private keys are disabled. (DEPRECATED)")},
            },
            want_psbt ? std::vector<RPCResult>{} : std::vector<RPCResult>{{RPCResult::Type::STR_HEX, "txid", "The id of the new transaction. Only returned when wallet private keys are enabled."}}
            ),
            {
                {RPCResult::Type::STR_AMOUNT, "origfee", "The fee of the replaced transaction."},
                {RPCResult::Type::STR_AMOUNT, "fee", "The fee of the new transaction."},
                {RPCResult::Type::ARR, "errors", "Errors encountered during processing (may be empty).",
                {
                    {RPCResult::Type::STR, "", ""},
                }},