Bug: JSON.parse(undefined) reboots the ESP8266

I've now included a test for undefined in my code,it is fixed for me.
Since the source code is the same for all systems I wonder what's going on. Might be a job for a long winter nights to dig into it.

Another bug is this one (directly after erase and flash):

>require("Storage").getFree();
=16
>require("Storage").eraseAll();
=undefined
>require("Storage").getFree();
=196608

Do you have the same on the ESP8266 4MB build? It doesn't affect the JSON.parse.