It would be nice if the debug console had a little help page of itself, to describe the syntax to issue commands (also the nested ones), and a disclaimer that usage can be dangerous.

Maybe add a debug-console-only command like help that shows how to use nested commands and potentially other advanced tricks, and add 'for more information on using this console type XXX'.

See also:
- https://github.com/bitcoin/bitcoin/pull/7783#issuecomment-248274853
- https://github.com/bitcoin/bitcoin/issues/8544#issuecomment-240970925
- #8912 Console command paths cannot be specified correctly with backslashes
char ch = strCommandTerminated[chpos];
        switch(state)
        {
            case STATE_COMMAND_EXECUTED_INNER:
            case STATE_COMMAND_EXECUTED:
            {
                bool breakParsing = true;
                switch(ch)
                {
                    case '[': curarg.clear(); state = STATE_COMMAND_EXECUTED_INNER; break;
                    default:
                        if (state == STATE_COMMAND_EXECUTED_INNER)
                        {
                            if (ch != ']')
                            {
                                
                                curarg += ch;
                                break;
                            }
                            if (curarg.size() && fExecute)
                            {
                                
                                UniValue subelement;
                                if (lastResult.isArray())
                                {
                                    for(char argch: curarg)
                                        if (!std::isdigit(argch))
                                            throw std::runtime_error("Invalid result query");
                                    subelement = lastResult[atoi(curarg.c_str())];
                                }