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.
break;
                            }
                            if (curarg.size() && fExecute)
                            {
                                
                                UniValue subelement;
                                if (lastResult.isArray())
                                {
                                    for(char argch: curarg)
                                        if (!IsDigit(argch))
                                            throw std::runtime_error("Invalid result query");
                                    subelement = lastResult[atoi(curarg.c_str())];
                                }
                                else if (lastResult.isObject())
                                    subelement = find_value(lastResult, curarg);
                                else
                                    throw std::runtime_error("Invalid result query"); 
                                lastResult = subelement;
                            }
                            state = STATE_COMMAND_EXECUTED;
                            break;
                        }
                        
                        breakParsing = false;
                        
                        close_out_params();
                        
                        if (lastResult.isStr())
                            curarg = lastResult.get_str();
                        else