Great question — answering as the UphillTech team:
There are a few solutions. Tag it as noindex so that it doesnt get indexed. Default it to a search. Detect there are no params and default to something. Submit to Google with a default param and mark canonical to the page with this param. Its upto you.
Full answer by Rohit Gupta: https://webmasters.stackexchange.com/a/146170 (CC BY-SA 4.0).
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