Latest Espruino build for Esp8266

Also, try adding: global["\xFF"].history=[];

It's a hack but it removes the command history - something that could have been using memory that would have stopped you saving.

Is there less flash to save() in with 1v84, can you hint me to debug it ?

There's more RAM, but the same flash. Address sizes have increased which means that slightly more RAM might be used for the same code, but I think the main issue is that because there's more RAM, more command history get stored (it's deleted if memory runs low). That means that more flash gets used up when saving, despite the code size being roughly the same.