Currently, we use `assert` in RPC code to document logic and code assumptions. However, it seems a bit extreme to abort all of Bitcoin Core on an assert failure in one of the RPC threads. I suggest to replace all checks with a macro `THROW_LOGIC_ERROR_IF_ASSERT_FAILS(condition)` that does what it says. That logic error will then be returned to the rpc caller and will include instructions to report the error to our issue tracker.

Any objections or naming suggestions for that macro?
"}\n"
                },
                RPCExamples{
                    HelpExampleCli("getblockstats", "1000 '[\"minfeerate\",\"avgfeerate\"]'")
            + HelpExampleRpc("getblockstats", "1000 '[\"minfeerate\",\"avgfeerate\"]'")
                },
    }.Check(request);
    LOCK(cs_main);
    CBlockIndex* pindex;
    if (request.params[0].isNum()) {
        const int height = request.params[0].get_int();
        const int current_tip = ::ChainActive().Height();
        if (height < 0) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Target block height %d is negative", height));
        }
        if (height > current_tip) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Target block height %d after current tip %d", height, current_tip));
        }
        pindex = ::ChainActive()[height];
    } else {
        const uint256 hash(ParseHashV(request.params[0], "hash_or_height"));
        pindex = LookupBlockIndex(hash);
        if (!pindex) {
            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
        }
        if (!::ChainActive().Contains(pindex)) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Block is not in chain %s", Params().NetworkIDString()));
        }
    }
    assert(pindex != nullptr);