message: fix volume isosurface picking
diff: @@ -17,7 +17,7 @@ export function eachVolumeLoci(loci: Loci, volume: Volume, isoValue: Volume.IsoV
  } else if (Volume.Isosurface.isLoci(loci)) {
  if (!Volume.areEquivalent(loci.volume, volume)) return false;
  if (isoValue) {
  - if (Volume.IsoValue.areSame(loci.isoValue, isoValue, volume.grid.stats)) return false;
  + if (!Volume.IsoValue.areSame(loci.isoValue, isoValue, volume.grid.stats)) return false;
  if (apply(Interval.ofLength(volume.grid.cells.data.length))) changed = true;
  } else {
  // TODO find a cheaper way?
  