I am not an emonCMS expert, but my understanding is the Wh accumulators should ignore the drop to zero and continue accumulating when your smart plug returns.
However, it appears that there might be a bug: Wh accumulator does not survive several reboots
I suggest you watch that thread.
Have you set up your emonCMS to see what happens?
The “Help” texts:
Wh Accumulator: Use with emontx, emonth or emonpi pulsecount or an emontx running firmware emonTxV3_4_continuous_kwhtotals sending cumulative watt hours.
This processor ensures that when the emontx is reset the watt hour count in emoncms does not reset, it also checks and filters out spikes in energy use that are larger than a max power threshold set in the processor, assuming these are errors, the max power threshold is set to 25kW.
and
kWh Accumulator: This processor removes resets from a cumulative kWh input, it also filters out spikes in energy use that are larger than a max power threshold set in the processor, assuming these are errors, the max power threshold is set to 25kW.