Using master. During startup, if you open `Window` -> `Console` and try and execute any command (can be garbage) `bitcoin-qt` will crash:
```bash
On branch pull/16118/local-merge

Process 89287 launched: '/Users/michael/github/bitcoin/src/qt/bitcoin-qt' (x86_64)
2019-05-29 09:57:56.276746-0400 bitcoin-qt[89287:939924] MessageTracer: Falling back to default whitelist
Process 89287 stopped
* thread #1, name = 'bitcoin-main', queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x8)
    frame #0: 0x00000001015158ba QtWidgets`QCompleter::popup() const + 10
QtWidgets`QCompleter::popup:
->  0x1015158ba <+10>: movq   0x8(%rdi), %rbx
    0x1015158be <+14>: movq   0x88(%rbx), %rax
    0x1015158c5 <+21>: testq  %rax, %rax
    0x1015158c8 <+24>: jne    0x101515942               ; <+146>
Target 0: (bitcoin-qt) stopped.
```

Not sure if just disabling the menu, like in #16118 would be ok, as a user might actually want to be able to run a command.
if (lastResult.isStr())
                strResult = lastResult.get_str();
            else
                strResult = lastResult.write(2);
        case STATE_ARGUMENT:
        case STATE_EATING_SPACES:
            return true;
        default: // 
            return false;
    }
}
void RPCExecutor::request(const QString &command, const WalletModel* wallet_model)
{
    try
    {
        std::string result;
        std::string executableCommand = command.toStdString() + "\n";
        // 
        if(executableCommand == "help-console\n") {
            Q_EMIT reply(RPCConsole::CMD_REPLY, QString(("\n"
                "This console accepts RPC commands using the standard syntax.\n"
                "   example:    getblockhash 0\n\n"
                "This console can also accept RPC commands using the parenthesized syntax.\n"
                "   example:    getblockhash(0)\n\n"
                "Commands may be nested when specified with the parenthesized syntax.\n"
                "   example:    getblock(getblockhash(0) 1)\n\n"
                "A space or a comma can be used to delimit arguments for either syntax.\n"
                "   example:    getblockhash 0\n"
                "               getblockhash,0\n\n"
                "Named results can be queried with a non-quoted key string in brackets using the parenthesized syntax.\n"