I guess it depends. Exceptions are slow, but if it's just one plugin throwing one exception per frame, my guess is you won't see your FPS drop significantly. Since every exception allocates an object though, it does add GC pressure. You might see some frametime spikes and microstutters over time.
Of course, it can add up if there are multiple plugins throwing exceptions every frame. Logging the errors will add overhead too, so my plugin will actually slightly increase the performance cost.
So it really depends on the volume, and generally speaking VaM will probably run more stable without all the exceptions. But in the end, spamming that many exceptions is a bug and should be fixed anyway
P.S.: Thanks for your review btw!