Do not check interactions outside plot areas

[SirYwell]

Overview

Fixes #4513

Description

I don't exactly know how to reproduce the exception, but it makes sense to be more defensive here, avoiding NPEs in situations the target location is not in a plot area.

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[PierreSchwang]

I do kind of suspect the issue being that we use getPlotAreaAbs in the listener, whereas in the class where the area is null we use getPlotArea - but I can't really look into how they function differently rn

[SirYwell]

I think the former is just on PlotPlayer rather than Location, but does the same actually.

[PierreSchwang]

Oh yeah, I see - in the listener the are of the player is checked (where the player is actually standing) whereas the location param of checkPlayerBlockEvent is the location of the block triggering the event. So those are most certainly always different - which is no issue in classical plot worlds ig

but the fix should make sense i guess