Let me be a little clearer. To be sure "Each state shall appoint, in such a manner as the legislature thereof may direct, a number of electors," is what governs. And, to be sure, Gov Wolf submitted the Republican slate of PA electors to the Senate archivist in 2016, when the margin was very close (and I suspect fraud in Philadelphia and Pittsburgh and other Dem strongholds was jacked).
What many of us are envisioning in 2020 closer election driven by Dem fraud...lots of late ballots, some "found" ballots etc. In PA, that vote is certified by the Dem Boockvar. Let's say that despite many egregious example of Dem fraud, Boockvar certifies for because, ya know, we don't have time to investigate every claim of a problem by the "clearly partisan Trump camp".
In that case, I would HOPE the legislature steps in...the legislatures are R in 29 States, including PA, MI, and split in MN and Alaska - here is the map.
My point is, Wolf certified at close but uncontested vote in 2016. If it is close and ugly, Boockvar may cert for Biden even if there are shenanigans and the Legislature doesn't do its job (PA's Legislature hasn't always had a backbone). But if Trump wins by, say, 2%, it shouldn't get there.
That's why this is no year to stay at home and just assume Trump will destroy Biden, though the oil slip was gold.