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 (ch == '(' && stack.size() && stack.back().size() > 0)
                        {
                            if (nDepthInsideSensitive) {
                                ++nDepthInsideSensitive;
                            }
                            stack.push_back(std::vector<std::string>());
                        }
                        
                        if (!stack.size())
                            throw std::runtime_error("Invalid Syntax");
                        add_to_current_stack(curarg);
                        curarg.clear();
                        state = STATE_EATING_SPACES_IN_BRACKETS;
                    }
                    if ((ch == ')' || ch == '\n') && stack.size() > 0)
                    {
                        if (fExecute) {
                            
                            
                            UniValue params = RPCConvertValues(stack.back()[0], std::vector<std::string>(stack.back().begin() + 1, stack.back().end()));
                            std::string method = stack.back()[0];
                            std::string uri;
#ifdef ENABLE_WALLET
                            if (wallet_model) {
                                QByteArray encodedName = QUrl::toPercentEncoding(wallet_model->getWalletName());
                                uri = "/wallet/"+std::string(encodedName.constData(), encodedName.length());
                            }
#endif
                            assert(node);
                            lastResult = node->executeRpc(method, params, uri);