Guard against getESSList() returning None ('NoneType' object is not iterable)

[szrudi]

Problem

getESSList() is declared -> Optional[list] and legitimately returns None whenever the underlying api_get() receives a non-success / empty payload or the Alpha ESS cloud is briefly unreachable (connection timeout, Cannot connect to host openapi.alphaess.com).

But getdata() and authenticate() iterate the result without a None check:

units = await self.getESSList()
for idx, unit in enumerate(units):   # 'NoneType' object is not iterable when units is None

So any time getESSList() returns None, the entire poll raises 'NoneType' object is not iterable (logged under the alphaess.alphaess logger and re-raised). Observed in the wild on a transient cloud hiccup:

ERROR [alphaess.alphaess] Connection timeout to host https://openapi.alphaess.com/api/getEssList
ERROR [alphaess.alphaess] Error: Connection timeout to host https://openapi.alphaess.com/api/getEssList when calling ...
ERROR [alphaess.alphaess] 'NoneType' object is not iterable
WARNING [custom_components.alphaess] Cloud API error: 'NoneType' object is not iterable

(The Home Assistant integration catches it downstream and falls back, but the library shouldn't throw on a return value its own type hint declares possible.)

Fix

Guard both iteration sites against None:

• getdata() logs a warning and returns the (empty) alldata list, so the caller keeps its previous data instead of crashing.
• authenticate() returns False.

No behavioural change when the API responds normally.

[CharlesGillanders]

Thank you!

Approved too soon

[CharlesGillanders]

Thanks for the PR, I'm happy to accept it but could please also edit setup.py to bump the version number?

[szrudi]

Thanks for the quick review! Bumped setup.py to 0.0.19 in the latest commit. Let me know if there's anything else you'd like changed.