Posible stack corruption after loading a date

Check this console session:
```
>> recycle/off        ;<--- to make sure it is not GC related issue
>> <a>
== <a>   ;<--- correct result so far

>> load "22-Feb-2019" ;<--- this seems to make a problem
== 22-Feb-2019

>> <a>
== <>   ;<================= WHY THIS?

>> b: 1 ;<----------------- this makes it normal again
== 1

>> <a>
== <a>   ;<--- correct result again
```