Local referencing cannot handle empty annulus

[zzhmark]

The local radius mode of common reference can fail when no channel is found within the specified the radius range (annulus).

In most cases it falls upon the user to find a proper range, but sometimes it's hard. In my case, I would first discard disconnected channels with high impedance, changing the local density of the contacts. A workaround is to maintain the channels, but those channels can introduce a lot of noise into the reference.

Do you find it useful that we can add some new features like specifying KNN or return to global referencing when it fails?

[alejoe91]

Hi @zzhmark

This is a good point. Yeah probably it would make sense in case no channels are in the annulus to maintain the channel, but add a warning (at init). Can you make a PR?