The new `getrpcinfo` shows a list of the active commands and the duration each command has been running. This sounds like a good place to report a completion percentage for any command doing a blockchain rescan, to solve [this problem](https://bitcoin.stackexchange.com/q/83236/90721).
}.ToString());
    }
    WalletRescanReserver reserver(pwallet);
    if (!reserver.reserve()) {
        throw JSONRPCError(RPC_WALLET_ERROR, "Wallet is currently rescanning. Abort existing rescan or wait.");
    }
    int start_height = 0;
    uint256 start_block, stop_block;
    {
        auto locked_chain = pwallet->chain().lock();
        Optional<int> tip_height = locked_chain->getHeight();
        if (!request.params[0].isNull()) {
            start_height = request.params[0].get_int();
            if (start_height < 0 || !tip_height || start_height > *tip_height) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid start_height");
            }
        }
        Optional<int> stop_height;
        if (!request.params[1].isNull()) {
            stop_height = request.params[1].get_int();
            if (*stop_height < 0 || !tip_height || *stop_height > *tip_height) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid stop_height");
            }
            else if (*stop_height < start_height) {
                throw JSONRPCError(RPC_INVALID_PARAMETER, "stop_height must be greater than start_height");
            }
        }
        
        if (locked_chain->findPruned(start_height, stop_height)) {
            throw JSONRPCError(RPC_MISC_ERROR, "Can't rescan beyond pruned data. Use RPC call getblockchaininfo to determine your pruned height.");