save() on espruino_1v91.122_esp8266 results in immediate Disconnected prompt

For a second sanity check, and as I have this flash procedure down pat now, again tried 1v91
Performing the save() command still results in an immediate disconnect:

1v91.122 Copyright 2016 G.Williams
Espruino is Open Source. Our work is supported
only by sales of official boards and donations:
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Flash map 4MB:512/512, manuf 0xe0 chip 0x4016
>
=undefined
>process.memory()
={ "free": 899, "usage": 801, "total": 1700, "history": 730 }
>save()
Disconnected

Engraved on chip shield:

FCC ID:2ADUI ESP-12
Model ESP8266MOD
Vendor AI THINKER