Handle MemoryError more gracefully

e.g. this code ran by a user:

```python
numbers = [3, 1, 4, 1, 5, 9, 2, 6, 5]
new_numbers = []
for num in numbers:
numbers += [num*2]

print(numbers)
```

leads to a `MemoryError`. It should just display something sensible in the console without crashing everything, showing an error dialog, reporting to sentry, etc.