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.
curarg = lastResult.write(2);
                        
                        if (curarg.size())
                        {
                            if (stack.size())
                                add_to_current_stack(curarg);
                            else
                                strResult = curarg;
                        }
                        curarg.clear();
                        
                        state = STATE_EATING_SPACES;
                }
                if (breakParsing)
                    break;
            }
            case STATE_ARGUMENT: 
            case STATE_EATING_SPACES_IN_ARG:
            case STATE_EATING_SPACES_IN_BRACKETS:
            case STATE_EATING_SPACES: 
                switch(ch)
            {
                case '"': state = STATE_DOUBLEQUOTED; break;
                case '\'': state = STATE_SINGLEQUOTED; break;
                case '\\': state = STATE_ESCAPE_OUTER; break;
                case '(': case ')': case '\n':
                    if (state == STATE_EATING_SPACES_IN_ARG)
                        throw std::runtime_error("Invalid Syntax");
                    if (state == STATE_ARGUMENT)
                    {