`TerminateSectors` params extraction may interpret empty array as `null`

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Describe the bug:

We have found a case where the TerminateSectors params contained the following:

{ "Terminations": [] }

Upon extracting this w lily via parsed_messages model, it comes out like this:

{ "Terminations": null }

This breaks the consistency of that value always being an array. It should be fixed to properly extract as {"Terminations": []} in the exported data.

Example: https://filfox.info/en/message/bafy2bzaceb7ncdapqvbefefczhc63afexfeytxhtgrix7dvk4jyvurribtfk2

Lily Version: v0.11.0