Getting lots of unavailable results on my sensors in the last few days

[snigehere]

@alanmcgore Thanks for putting this useful integration up and sharing the charts you produced.

I have been using the integration for the past 3/4 weeks and please with the info it provides but the back end of this past week I have noticed the sensors showing "Unavailable" quite a bit ... as its on my main information panel it stands out .. I am assuming some issues in fetching the data and wondering if there is any retry function in the code if it does not get a response...

Debug shows:
-timestamp- ERROR (MainThread) [custom_components.carbon_intensity_uk] Error fetching carbon_intensity_uk data: 'data'

and then an error from the template as no data (I assume)
-timestamp- WARNING (MainThread) [homeassistant.helpers.template] Template variable warning:

Any pointers or help would be appreciated
Thanks